With a SAAMI max pressure of only 23k psi- versus 30-35k psi for many commonplace pistol cartridges- I can't imagine that .45GAP could really be considered unforgiving. It's theoretically less forgiving that .45ACP, but that's only because .45ACP is one of the easiest pistol cartridges to handload this side of .38Spl or .44Spl.* It shouldn't even be placed in the same category as another common pistol cartridge that has relatively high operating pressure AND very little case capacity (cough... forty... cough).
Same with case life; low chamber pressure generally extends case life. I don't see the cartridge having a problem here either.
All that said, .45GAP DOES come up short in two respects vs. .45ACP due to its smaller case capacity: (a) it doesn't handle 230gr bullets nearly as well because the larger bullets approach its case capacity limits, and (b) velocity of top-end loads is slightly higher in .45ACP because of the extra empty space in the case.
*Provided that the cases aren't double-charged.