For XC type riding I much prefer my 29er (scandal, not built up particularly light), it does roll over small bumps/roots/logs better, takes bumpy washboard type stuff better, and is so quick once you get it wound up, just seems to keep momentum and allow me to climb faster than I have any right to. Yesterday I was slightly dreading one bank on the way home, near the end of the ride, but was at the top before i knew it.
On the flip side, it is slightly more cumbersome in the tight and twisty stuff, and on steep descents I’d rather be hanging my arse out over the rear of a 26″ bike, it’s just more fun, though the scandal is very XC orientated IMO.