I'm still suffering this aspect of making a decision. I recently had a chance to ride an M6L in El Segundo, CA where it was a bit hilly and wondered if 3 speeds wouldn't really be enough for my use which is primarily paved bike paths in Idaho and SoCal. I just ride for the fun of it so as long as I can get up mild hills without walking the bike, I'm good.
Most dealers I've talked to save for NYCE seem to order their stock bikes in 6 speed, especially the west coast dealers. It's only a $100 or so but they're so dang expensive already that I'd like to save some money if I can.