XTP and GD both are made with soft lead cores swaged into a gilding metal jacket. The lead in the core doesn't stay together worth a dang once the jacket is shed, it is frangible and pieces of it break off the core rapidly once it loses the jacket.
The wide meplat of the 45 caliber projectiles is already as large as a fully expanded and mushroomed 30 caliber jacketed bullet and we all know how lethal that is, so now you have the lethality of the expanded 30 caliber, with the momentum of a much larger and much heavier boolit, and an alloy that is tough but still malleable enough to stay together (where it retains much of it's original weight) so a complete pass through is pretty much the norm.
I got away from the XTP when I started having to pick through a wound channel for tiny pieces of bullet material, definitely didn't want to eat right up to the hole with a mess like that.
Haven't taken game with the OWC yet, but it's first up as my go to handgun load for the deer woods. No HP needed, nor recommended.