Some 29ers have a floppy front wheel because of the slack geometry combined with the taller headtube. The tall front is also a liability for steep climbs in my opinion. If you use the bike on extended climbs consider a shorter fork to get the front of the bike lower. Some people have put rigid 26" forks on 29ers, also 27.5". Yes it steepens the frame geometry and lowers the bottom bracket one or two cm, but some people consider these benefits instead of liabilities. Alternatively, if you're considering a rigid because the front end seems far too high, you could install a freaky stem like the Satori Turn-Up or Cobra but keep your existing fork to get the handlebars lower then the headset. You can also install riser bars upside down, or road drop-bars.