I did my Courchevel altiport rating last March with Robert Christin and would highly recommend it. The "Aeroclub des Trois Vallees" is primarily him I think with some admin assistance.
Two aircraft - C172 (wheels) and Jodel D140 (Skis/Wheels) - both very tidy and quite comparable to aircraft I have flown here in the UK at my local flying club.
Took about 5 hours which included a trip around Mont Blanc at about 12500 ft in the C172 - getting up that high was interesting - and if you get the chance go to the St Sorlin glacier in the Jodel with RC for a couple of circuits and maybe a full stop landing.
I spent most of the week while my friends were skiing flying and completing the Courchevel rating - some of the best flying I have done to date.
TZ