Originally Posted by Mariov
Having to buy new alpine skis, I would like the flexibility to use them for some occasional mountaineering trips.
If I buy randonee, are there downsides in using them locked on normal ski resorts?
Yes, there are downsides:
AT (randonne) gear is designed to be light and allow touring, this means moving parts made out of light materials. Flex is an issue with most AT bindings, stand height is an issue (for some) with AT bindings, safety can be an issue. Oh... and they cost WAY more.
AT boots don't fit or perform like high performance Alpine boots, not an issue for many people, but for some it REALLY matters.
Any flat ski can be an AT ski, the lighter the ski the better it will be for AT, light weight is neither good nor bad for skiing on lifts, it's preference.
I'd say if you Alpine ski a lot buy an alpine set-up, it will perform way better. Alpine Trekkers and skins will let you tour (sort of) if you want to try it. If you tour a lot and only ride lifts occasionaly, buy an AT set-up and use it for both. If you do both a lot you really need two set-ups.