Flounder speaks the truth, btw, about the technical uphills, including switchbacks. And it's something that surprised me when I first got on a 29er because I had read over and over about how they "accelerate slowly." So I'm thinking of the super-steep and loose climbs we have around here and the way that I often come to a complete stop, regain my balance and then have to turn the pedals again to keep going...
Guess what? The way 29" wheels roll makes them IDEAL for that. In fact, I would say that a 29" wheel's #1 advantage is technical, rocky, loose, slow-speed climbing on steep stuff.
IMO, most of the myths about 29" wheels are... myths. Armchair physicists poo-pooing, is all. I actually bought a 29" bike because I didn't believe and wanted to be able to say, "I owned one and it was awful." Then I rode one and found it was faster, just as nimble, quite a bit more comfortable, climbs really well and the wheels are not any weaker than 26" wheels (for my applications).