I have both a No4MkII Enfield and a Garand. I've used both in formal rifle classes, as well as informal plinking and target shooting. I do love the Enfield, but I'd definitely grab the Garand if I needed a rifle right now.
Stripper clips may be quick and efficient in theory, but they can be a real pain in practice. I can definitely reload the Garand faster than the Enfield.
As for the ammo issue, I think it's a moot point for a SHTF rifle. If that situation does occur, you will be carrying the rifle around a lot and shooting it very little, much like a hunting rifle. A box or two of ammo would most likely be all you'd actually need, outside of extra for practicing. So you can easily stock enough for actual needs. And if you can't, it's not like a handful of heavy commercial rounds will explode your M1. Heck, if all I had was milspec FMJ and heavy hunting softpoints, I'd keep the rifle loaded with the heavy stuff. If I need to shoot someone, I'd rather have the more effective ammo, and worry about the rifle's long-term health later.