I purchased a single speed mountain bike and my exact words were "I'll never get into mountain bike racing anyway" So 4 weeks later in my first mountain bike race I understand why mountain bike usually have gears. I have this year became a lot better mountain biker (still not that good though) and this has seriously reduced my road milage the end of this year (not going to make my 10k goal) but I enjoy mountain biking even when I'm off the back alone. So I do think a multispeed 29r is on the radar for next fall.
I haven't been on a geared bike (unless you count my crappy commuter) since The Dr Bob ride in september. I am looking forward to my touring bike next year for a little more multispeed riding. However multispeed is for going faster not for slowing down.
I have put together a multispeed cross bike from an old mountain bike to see how my first cross race will go (jingle cross) I'm not trying to win just to survive.
So all together I don't know Road races, Touring, Cross Races, Mountain Races, Mountain rides, Commuting, and Road rides I need more hours in the day. And another new bike.