I too have de-primed a lot of live primers...not hundreds but a cpl dozen...and with no problems.
I do think that since the decapping pin is pushing down on the "anvil" portion of the primer's interior, it may crack or damage the "pellet" which is the firing compound. For me, that negates reusing them...I want consistent ignition in any rounds I assemble...a damaged "pellet" makes that problematic. I'd not trust the rounds so assembled.
I also think that if you're using that .45 ACP as practice ammunition, and you are doing defensive drills which include double taps or controlled pairs, you may risk lodging a bullet in the barrel with disastrous consequences.
Our Flag does not fly because the wind blows against it,
It proudly waves because a soldier's dying breath blows upon it.
USAF Forward Air Controller, 5th Spl Forces,
An Loc, lll Corps, RVN, 69-70, Vietnam Vet '69-'73