+P will be fine in the MP45. .45 ACP isn't a real high pressure round to begin with, 18,000 PSI or so, with +P .45 being around 23,000 PSI.
In contrast, many 9mm and .40 loads are in the 35,000 PSI range, with 9mm +P and +P+ up to 38,000 PSI.
Since you were given the ammo, might as well use it, but I'm not sure why someone would pick a .45 and want to use 78 grain loads in it. That's really high velocity, but I doubt it would give 12 inches of penetration like is claimed on the box. Most 185, 200 and 230 grain .45 ACP loads will only get 13 or 14 inches of penetration in gel.
Kind of a novelty,gimmicky ammo.
I agree that's somewhat of a gimmick, special purpose ammo and probably too expensive to use with any regularity. Shoot it with no worries about damaging your gun but replace it with more conventional ammo for regular use.
Any +p ammo will tend to cause more wear, but it shouldn't damage your firearm. Liberty Civil Defense (previously known as Halo and USM4) it's a poor choice for personal defense. Might be a good coyote round.
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