Use what works for you. I use crab with a kick straight and wing down just before/during the flare. I just personally dont like a long wing down final. To each their own however.
I am with Jason. When I was a freshly minted pilots I had problems with crosswind landings and it took me a while to get really comfortable with them. So back then I tended to transition from crab to sideslip earlier on final. Now I transition to the sideslip fairly close to the ground, probably something like 15 feet.
In a tailwheel the side slip technique will give you a good indication whether you will be able to land in the crosswind. I prefer landing two-point, upwind main gear and tailwheel, to a wheel landing.
Most vintage tailwheel, Super Cub and 180 excepted, are not blessed with effective drag flaps, or any flaps, so the forward sideslip was necessary to help steepen approaches over obstacles and help with crosswind landings. They have surprisingly good crosswind ability, it is the subsequent taxi in quartering gusty conditions that make them exciting. As alioth points out, there is unlikely to be a departure in a forward sideslip, although extreme provocation will yield a departure opposite the sideslip. That is, the higher wing will depart so you would roll towards the higher wing. This is the opposite of the skidding turn where the departure is towards the lower, retreating wing.
The main incorrect technique I see in a sideslip, is allowing the speed to build up, which defeats the object of the sideslip!
I can sympathise with the instructors in underpowered, barn door Cessna 150 flaps. Lots of incidents of students struggling on go arounds, with enough fatal incidents that the 152 introduced gates on the flap lever and reduced max flaps to 30 degrees. With 40 degree semi fowler flaps there is no advantage in also using a sideslip, the steepness of the approach is not increased, and an inexperienced student may have their hands full figuring out a go around from a side slip with full flaps. Instructors calibrate the flight envelope for the students experience and don’t want them using a technique which the type was not ideally suited for.
On the MEP there is very little propeller clearance, at least for the low wing configuration. Landing in a side slip will raise the risk of a prop strike, plenty of incidents confirm this, in addition to w_n’s point of uncovering fuel ports. Therefore most schools instruct the crab method, also I believe the preferred method for underslung jets. When you straighten the aircraft using rudder in the landing flare, this yaw will result in the upwind wing rolling and the roll will be exacerbated by the crosswind, hence the need to introduce into wind aileron to keep the wings level, in some types a lot. It’s not unusual to need full into wind aileron when you have straightened the aircraft in the flare, this is not, however, a sideslip.
A one-point landing is possible on a smooth runway with a crosswind when, as speed decreases, the controls lose effectiveness, and can no longer hold direction. On a rough runway, this could lead to bouncing at an airspeed where control was impossible.
This is with a low inertia aircraft.
On the MEP there is very little propeller clearance, at least for the low wing configuration. Landing in a side slip will raise the risk of a prop strike, plenty of incidents confirm this,
That’s interesting, could you point me to a few? I have flow quite a lot of different MEPs, and I can’t immediately think of one where the mainwheel is sufficiently displaced inside the engine centre line to make this possible. Mostly they are either on the engine centreline or outside it, both of which would preclude a propstrike. I guess that there are a few where the mainwheel is connected to the fuselage, but these tend to be high wing where a propstrike would be impossible.
I have many more hours on MEP than SEP or jets, and I have only ever used wing down, even in the strongest crosswinds, and have never been anywhere close to a propstrike.
So, genuinely interested.
Ground clearance getting a bit tight on the DA42 (looks like about half normal clearance). More worried about the wing tip here
Cobalt – that is a very good daigram.
I used both techniques in the 42, and I cant say I ever felt it was a concern, but your diagram suggests the clearance is less than comfortable in the extreme.
I think that that demonstrates that propstrikes are not an issue even in that extreme situation.
But this just seems to be an OWT. I have landed in very stong (extreme, really) cross winds for a very long time and I have never had a bank angle exceeding 10°.
Yes, but you’re a Sky God. 
Personally I’ve seen enough bent props despite nice little pictures like the above.
On what type(s)?
Have not had an incident myself, gratefully, but am aware of incidents related to the PA-34 and PA-30. Quite a few MEPs are not that tolerant of side loads on the main gear, and can also think of main gear folding on the upwind gear. Obviously the absence of any crosswind technique will place unnecessary side load on the downwind leg.
