We did compare the two lamps by swapping between them quickly, and there was no visibly obvious difference. They both illuminate the wing perfectly well. There is a massive difference in the heat generated, obviously.
The company sells direct. And (if you ask) ships by airmail, which is very unusual for US firms who mostly are unaware of the Post Office system 
One problem is that all the holders for this bulb type are frankly crap. They seem to be out of a 1970 Vauxhall Viva, and probably are the same part. I had to modify mine with a pair of pliers, to make it hold the bulb tightly.
Too bad I see this now, I would have ordered 2 as well…
What about the light intensity, is it the same as the original, or maybe better?
The LED lamp works at least as well as the original one and draws 1/10 of the current. The original one would really heat up the fitting and everything else around it.
Just arrived
It draws just 0.17A at 28V.
This is the original filament lamp in its fitting, on the TKS-converted TB20
No interest so I am buying a couple so will have a spare, possibly for sale. Alphabeam, unusually for a US firm, will ship by airmail, which saves a load on the usual $200 cost.
Is there any interest in getting some of these?
The above lamp, @AdamFrisch, is $135 plus shipping. Is anyone interested in buying these so we can buy several and share it out with paypal?
In particular, as is common, the firm won’t ship outside the US except by a courier (they are not aware the US has a postal service 
) which is another $200 or so, so it would be great to find someone in the US who would put one in a cheap ($10) airmail package.
I’ll probably do the same on mine – this ice-lights are terrible.
That is another good find but I suspect (looking at the LEDs) the power would be too low.
So I will try to get the Aeroleds one mentioned above
The other good thing about an LED lamp is that the present one runs really hot and the whole lamp assembly heats up to something mad. It draws 1.5A at 28V, so this is not surprising.
