I wouldn't run anything else. I'd say the shop guy would of been talking bout guys going single speed on there XC/enduro bikes maybe. For dirt n street you will only use 1 gear anyway. Basically always going the same speed, etc. Plus its 1 less thing less to break, less weight, don't have the chance of your chain coming off, and mostly for me its quiet and chain not slapping around. Best choice I made when buying my new bike. Unless your gonna be riding DH would be the only reason I'd run gears, and then still I'd be happy with running a bigger gear on my single speed to matchvtue extra speed I'd be running at.
26T x11T or 28T x 12T is a good gear ratio. Or equal ratio with a bigger rear gear like 16T if your using a single speed conversion kit and can't run the small reaer sprockets.
Hi just found this thread looking for one on Single speed on DH bikes, any body here know if there is one? As for Regretting SS, I recently went SS on my Bolt Build. after years of 4X racing, I was only running 3 speed anyway so thought I'd go SS to save some weight. Nope, No Regrets. It's taught me to rely on flow an a smooth style rather than mashing pedals hence the decision to try it on the DH bike.... cheers
It maybe worth starting a general singlespeed thread as this was the only one I could find.