The forum comments I've read about reloading .357Sig
I would think that when he speaks of "easier loading" he means more the feeding of the round into the barrel. Bottleneck cartridges do tend to feed more easily in a semiauto than straight walled rounds. But for reloading, yeah, I can see how they would be harder to reload.
I'd like to try out the .357 Sig, and a conversion kit for my P250 would be reasonable enough, but ultimately the ammo cost may hold me back. It costs quite a bit more for not much more capability than the 9x19 currently provides- sure, it's moving faster and you'll get better penetration, but the bullet is the same size. Unless I could place a shot better with .357 Sig it wouldn't be of real interest since I'd lose magazine capacity.