I guess I've only got a couple things to really add to what others have already said:

First, if you're wanting to get 1500fps (or more) out of your "mid-range" loads I would really recommend shying away from the regular XTP bullets. You 'might' not have trouble with them at 1500, but you 'will' have trouble with them if you go much more than that. You can push the XTP-MAG's pretty hard without worrying about shooting them apart.

And second, you can probably shoot an awful lot of .45 Colt loads before you'll get any sort of ring in the chambers that would prevent you from insterting a .460 case (especially if you use cleaner burning powders)... and you might get "sticky" extraction but you wont get "stuck" cases caused by a ring unless you completely neglect proper cleaning.

I've got a .454 Casull and they are notorious about difficult extraction with yowza-hot loads. I typically shoot 2-300 .45 Colt loads when I go to the range, followed by .454's and there isnt enough of a ring to make a bit of difference.