I didn't make it clear (and actually, pretty much wrote the wrong thing).
The numbers I mentioned before in terms of cloud are my departure minimums at EGLM. I might move more towards the legal departure minimums if I had one or more of:
2km of tarmac Full ATC with radar A second engine
My destination minima are my legal minima for the approach I intend to fly. I understand this to be 500ft for a precision approach and 600ft for a non-precision approach. However, I've never seen this in anything from the CAA. All I've read is training texts saying that IMC-rated pilots should use those minima. I've always taken that as legal minima, but then the same text says that "GPS should never be used for primary navigation" :-)
Taking the minima to 200ft makes what difference exactly?
I think the ability to go to minimums also depends on equipment. Although now the IMCr minimums have apparently been removed, i'd probably not consider a minumum lower than 600 ft with an ILS approach, and 1000 ft on a non-precision approach, including a VOR let down at the one near my local airfield. Maybe thats because on the IMCr one isnt trained to 200 ft minimums. Even then, I dont think I would change my view. Sure, if you have a decent flight management system, with integrated approach charts and a very precicely coupled autopilot, then I'd consider it. But in my aircraft, albeit with a GNS430, I wouldnt as the autopilot is pretty basic and even though it is coupled to the Garmin, it is far from precise, with no altitude or rate of descent control, thereby increasing my cockpit workload such that I wouldnt go down to the minimums. Just my view...
Have the IMCr minimums been removed? Can you provide a reference?
I've no problem flying an ILS to 200ft, I just don't do it because I assumed it wasn't legal.
I flew them to 200ft a few times during my IMCr training (at instructor's insistence) and didn't find it unacceptably taxing. I found that the last few hundred feet happens pretty quickly, and as long as you have the approach stabilised there is not a lot of time for much to go wrong.
If I was flying an approach that was unstable enough that I didn't think I could fly it down to 200ft, I would probably have already gone around well before 500ft anyhow...
Flying a FIKI approved aircraft with a ceiling of FL250 means for me that I can basically always fly, except for developed build-up TCU/Thunderstorm stuff. During the last winter I was able to basically fly every planned flight. Not one excepted. Snow, rain, ice (except for severe icing / severe freezing rain) did not keep me from getting to my destination. The most critical in these was the deicing. That made it possible to depart when others had to stay home.
I found that the last few hundred feet happens pretty quickly,
Well actually they happen in the same amount of time as the few hundred feet before them! :)
I have found a very high despatch rate (legal I should add) with a deiced aircraft that can go to FL250.
Which is what I wrote, which was
or in general something with
* full de-ice
* radar
* an operating ceiling above FL250
which is what you have on your PA46. A PA46, along with a PA34 and a few others with boots and radar, represents the entry level for serious convective wx and icing penetration. With a bold pilot and tough passengers, these planes should achieve 98-99% despatch rate in Europe.
Have the IMCr minimums been removed? Can you provide a reference?
The IMCR minima are the same as the IR minima, except
There has been the usual diatribe written over the years about the MDH not being below 500ft, etc.
Sure, having decent equipment helps greatly. A coupled autopilot is the best 
Personal minima is a personal thing. I never used it, and would always fly down to the MDA on the plate. But not everybody is as current as they would like to be (which private pilot is, really??) and not everybody has a plane with a lot of nice kit that 100% works. A lot of people are in syndicates where no agreement is reached on fixing stuff, so they need to be more conservative. Or they rent stuff.
On the basis of the METAR, I don't think 99% is far off
On the basis of that METAR, you can fly 100% of the time VFR and 100% of the time IFR
But that's not the same as having a 99% despatch rate on a flight from A to B, where the given conditions prevail at the two ends.
If A to B is say 50nm then it can probably be flown under the cloudbase (VFR) or, ahem, under the cloudbase (IFR, UK, Class G).
If you take off, fly a circuit, and land, your dispatch rate will be even better.
But a Eurocontrol-filed IFR flight (lowest level perhaps FL070, usually FL100) may not be possible due to e.g. icing conditions higher up.
Anyway, the OP was just a statistical analysis of a given airport, which is interesting.
One could expand it to analysing two airports say 100nm apart, for which one can get METARs at several points in between, to guess the likelihood of "VFR under the cloudbase". Obviously, that figure will be lower than the chance of a "VFR" METAR at just one spot.
Well actually they happen in the same amount of time as the few hundred feet before them! :)
Have you noticed the HSI sensitivity increasing as you go down the LOC/GS?
You have either been trained to get to 200ft or not. If not, you shouldn't be flying to 400ft or even 800ft.
Taking the minima to 200ft makes what difference exactly?
I would never commence an approach with a ceiling of 200ft AGL and I never have in my IFR career. During training, it was all simulated IMC and that is very different from real IMC (turbulence). 200ft is extremely low and every little mistake can be deadly. Small aircraft are very sensitive to wind shear and this is what you typically encounter a few hundred feet above ground. The lower you get, the faster you are off glide slope. 200ft requires serious training and currency.
During my training I did fly an approach where I started at fl130 on top and arrived at 200 feet just breaking through ..the rvr was also limited. I flew the entire approach manually and it was fine.
The discussion is basically not what you can do but what you are willing to do. I am deiced and have a fl250 ceiling but I have no radar. A stormscope is a nice add on but it does not replace radar.
I did an approach into Reus where I was inblue skies until the pyrenees, inthe cloud and then inbetween the clouds above the mountains and when I had to start the approach I dived into a cloud where I was climbing harder then I could descent. Then there was thunderstorms over the Barca Reus area and all the big birds were going 10 right 20 left etc. And there you are bouncing down The approach in the clouds without radar..
I decided there and then that that was not a good place tobe. That is why I added the mlx770 irridium phone and the Twx670 .. together with the 2 IFD540s (when they arrive).
I fly strictly for fun. I do not mind going through the clouds but I do not Enjoy a flight where you are 90% in the clouds. Thunderstorms in the area ..only if not embedded so you can see them coming.
Ice .. no thank you .. no need totake risks .. unless you know you just have to climb through a layer. Snow is a non event .. wet snow is a different issue.
Take off with a 200 feet ceiling.. mmmm .. the old what if efato discussion. It will depend on how necessary the trip is and how the weather is along the way.
For the most part I am interested inwhere the tops are and thusfar I only found Jeppesen Internet flight planner and topmeteo.eu as source that give me a good impression of how it could be out there.
Well actually they happen in the same amount of time as the few hundred feet before them! :)
You know what I mean! ;-) Any 'few hundred feet' happens pretty quickly, whether they are an early few hundred feet or a late few hundred feet.
Have you noticed the HSI sensitivity increasing as you go down the LOC/GS?
Of course, although I've only flown a few ILS approaches with a HSI - our TB10 is old school DI/OBS. I found the HSI infinitely easier.
The best piece of advice I got from one of my IMCr instructors was to fly the approach clean at cruise speed. This means the aircraft is more stable and because everything then goes from start to finish much quicker 'holding the needles' doesn't become as tiring. This works fine in a TB10 where one can fly the glideslope at 110kts and (even at 200ft) suddenly cut the power, drop the flaps as the airspeed falls into the white arc and continue the same descent angle at a nice easy 75kts onto the runway. I appreciate that in higher performance aircraft which would have to scrub off more speed, this wouldn't work (although you could maintain a high-ish glideslope speed, just not as high as the cruise speed).
I would never commence an approach with a ceiling of 200ft AGL and I never have in my IFR career. During training, it was all simulated IMC and that is very different from real IMC (turbulence). 200ft is extremely low and every little mistake can be deadly. Small aircraft are very sensitive to wind shear and this is what you typically encounter a few hundred feet above ground. The lower you get, the faster you are off glide slope. 200ft requires serious training and currency.
I was relatively lucky in that most of my IMCr training was in real IMC.
Cloud that close to the ground tends to be more stratiform and not particularly bumpy, but of course you can't rely on that as a given.
As I just mentioned, keeping the speed up makes the aircraft more stable and less likely to wallow with every gust.
Would I commence an approach with a reported ceiling of 200ft? Probably. But I'd be very strict about go-around criteria. To some extent it would depend how far away my alternate was and what weather they were reporting. If everywhere is socked in, one simply has to get down. Not a nice situation to be in, but it could happen.
Would I depart when the destination was reporting 200ft with no forecast improvement? Probably not. It would depend on how current I was feeling and how much I wanted to get there.
