If most guys are riding 26FS , why not 29FS ?
Is it not the best of both worlds.
Like Norm said, it is mostly preference. However, what one *thinks* they prefer may not be what they really prefer.
But to answer your question, the 29" wheels (especially with some high-volume rubber) dampen the bumps better than their equivalent 26" cousins. So it is conceivable that a 29" HT might ride well enough for somebody through the rough stuff, where a 26'er HT might be a little rough. So, it is possible (I'm proof) that somebody on a 26" FS might find a 29" HT just fine. If a 29" HT were to work for you, you'd save money and have less to maintain and deal with. The weight thing isn't such a big deal; my Niner SS (27 lbs) only weighs 2-3 pounds less than a geared and comparably equipped Turner Sultan (29 'n change...*maybe* 30lbs).
I started riding again last fall after well over a decade off the bike. My progression looked like:
- 26" HT; Specialized M2. Pummeled the CRAP out of me at MD.
- 26" FS; Turner 5-spot. I have a bad back and knew my body couldn't take much of that. I really hadn't gotten a bead on the 29'er thing, so I focused on a FS 26'er. Great bike, but in the end, didn't fit my riding style/preferences/whatever...
- 29" HT; Aluminum. Loved the 29" wheels, but in the end the aluminum was a little to rough for me.
- 29" HT; Steel. Ahhhh, just right. My knees are garbage, my back is garbage, I'm 43 years old, and I don't miss the FS 26'er back end.
My point here is try, try, try, try, try to get some time on various bikes and see what works for you. Bug friends; take advantage of demos at shops; go for rides with crazies from here and ask to try their bikes (hey, the worst they could say is "F' off")
I assumed a 26 FS was it and in the end, it cost me a lot of money to get to where I got (if you look at my bikes you'll see I don't do things half-ass either). If I'd ridden a Mary, SIR, whatever before I bought my Turner, I'd probably have two fewer bikes in my basement. In the end, if a 29 FS seems like the configuration for you, writing the (bigger) check for it will be easier.
What size bike do you ride? If you ride a large, after the "new" is gone from my SIR9 this fall (my head would explode seeing somebody else on my shiny new Niner right now), you're welcome to ride it. You can at least check 29" Steel HT from the list. When I get my Rig together, and if you ride a large, you can ride it too so you can check a 29" Aluminum HT from the list. Warning; they are single speeds...though by then I should be able to make my SIR9 a 1x9 when the mood strikes me