On second thought, there is one possible difference between the regular style and S-Type that could matter. The bag has one buckle on the strap, for you want to drop your bag in a hurry. This buckle is in front of you when you're wearing it "correctly", i.e, resting on your right side for the regular, or left for S-Type. If you anticipate or want to be prepared for drawing a weapon or getting in a fight, or running away/from danger in an emergency, it'd be a bit awkward to reach behind you for that buckle. Also, having the buckle in front of you would prevent your friends from pranking you by unbuckling your bag from behind you all the time.