We’ve just (literally, half an hour ago!) got back from our first week in the Alps, including the Pass’Portes du Soleil which two of our party did on 29ers – myself on a 120mm Salsa Horsethief and a mate on a 140mm Spec FSR.
Apart from the PPdS we spent days at Chattel and Les Gets doing the green/blue/red downhill trails. We’re both reasonable riders with little downhill experience and neither of us felt out of our depth with our choice of bike. To be honest most of the DH trails we did I would have quite happily done on a HT – we were quite surprised at how smooth most stuff was, except for the monster braking bumps!
Maybe the blacks are another story but, even so, I’m sure a suitable 29er could be found to do the job..