The problem everyone is having right now is that there are no bike to try. You can't even test out the size M and size L in the parking lot let alone get a demo ride on the trail. There just aren't any bikes.
FWIW, I'm 5'10" with a 31.5 inseam and I ride the L. I think I have a long torso and short legs. I don't know, maybe I just like the feel of the L and because I couldn't compare that against a M I just bought it since it felt great after demoing it on every local trail I ride.
I like this bike more and more with each ride. Just riding on the sidewalk and the playground grassy hills with my 5 y/o daughter is fun.
If I had the cash I would certainly buy a Specialized Enduro for the days when I want something slacker and more plush but those days are few and far between and I think that's why the SB is so appealing.