I agree that it's easy to load your own ultra-hot 45 Colt rounds. When I got my BFR 5-shot .454 Casull, I made some really hot .45 Colt rounds that nearly equal the .454 just like John Linebaugh talks about. No problems at all with the gun or the brass. Once I got enough .454 brass, I kind of quit making the super hot .45 rounds. I was afraid I would accidentally put the super hot round into one of my weaker revolvers. I've wondered about how strong the various .45 Colt lever actions are. I know Puma used to make .454 and .480 Ruger chambered lever actions. So, I'm guessing their .45 Colt rilfes are plenty strong as well. But that's just a guess at this point.
If I didn't reload, I would probably stick with the .44 mag though. It's easier to find hot .44 ammo than it is to find hot .45 ammo. Plus, if you are stuck with buying factory ammo, the .45 Colt stuff is expensive and sometimes hard to find.