My first years 15 of backpacking were spent in the UK and the next have been here in New Zealand. I never used UL shelters in the UK, but have used three (but not extensively)in New Zealand. Currently I have a TT Squall, a MLD Duomid and a MLD Trailstar. I use the Squall for below the bushline summer camps. It is good in heavy rain and I have modified it a bit to make it better in winds.
I have been blessed with calm conditions so far when using the Duomid, but did give it a strong wind test pitching near my house. I concluded that because of its height it was best for moderate winds.
Only two nights in the Trailstar so far and again very clam. A test pitch in strong winds is planned and I will report results. My initial impressions is that it will do well when pitched low and used with good stakes.
I have had a three pole geodesic tent badly bent out of shape, in the tail end of a typhoon that hit us at a low level camp near Wellington (not called Windy Wellington for nothing).
From the blogosphere I have seen a number of people are using UL shelters in UK conditions with success. However, everyone of course has different expectations of what success is. Do you want to have a tarp pitched 6 inches above your face whilst you are in an eVent bivy? The following seem to be the most popular in the UK.
1. MLD Duomid - however not everyone thinks these are up to strong winds and I would agree.
2. TT Scarp - works well, but is a std tent really.
3. MLD Trailstar - the current fave and a number of reliable reports of it working well in 60mph winds. http://www.andyhowell.info/Colin-Ibbotson/Trailstar-review.html. http://summitandvalley.blogspot.com/2011/01/rain-wind-and-sometimes-it-was.html
4. Tarps - These are definitely in the minority. See here for details http://www.andyhowell.info/Colin-Ibbotson/Colin-Talks-Tarps.pdf.
To conclude I do think UL shelters can work in conditions outside of the USA. However, if I was summit camping in Scotland, on a regular basis, I would probably look at a tent of some sort. I strongly favour designs where the poles are attached to the flysheet rather than the the inner, with the fly then stretched over them. If you want to go the tarp route have a look at the Trailstar.