I just did quite a long ride on my 29er, in full on XC mode, and it looked after me admirably, not a whisper of a moan from back or bottom. It’s done Peaks, trail centres, short course XC with nothing but tweaks to the cockpit (bars’n’stem).
I’ve never done a ride like that before and the bike looked after me admirably, but with the modern 29ers having had the steerer angles, forks etc sorted it’s plenty zippy in the singletrack. I’ll be using it on the legendary singletrack at the BrightonBigDog race later in the year. Can’t wait!
I also have an inbred 29er SS and it’s similarly fantastic. Have a P& rigid SS and the inbred is not precetably more ponderous or slow out on the trail: gears, forks, bars stem and tyres all make much more difference to the feel of the bike.