I have fired approx 2700 rounds thru my (3)G30SF's. About 1500 of those were the Fed HST 230gr +P's. My G30's eat them like candy, very soft shooting and extremely accurate. Hence that is what I carry in them. I figure an extra 50fps performance from a compact 45ACP can't hurt with the 230gr being the benchmark in ACP.
As for the GAP, I just picked up 2 of the G38's (same as a G19 in size,) and a G37 similar to a G17 in size. There is plenty of 230gr FMJ ammo in 45GAP ammo in Fed and Rem available locally. There is a ton of the Speer GD in 200gr available as well. I have close to a case and half of that. At $22/box of 50 rds., it was too good to pass up.
The GAP by the way uses a strengthened case and is loaded to plus P already, so there is no room to make an actuall "plus P" round for it. If I remember correctly the GAP in it's configuration is equal to reg. 45ACP balistics, but the 45ACP in plus P's outperforms it.
I feel more than moderately protected when carrying either the 45ACP or the 45GAP.
Just so no one thinks I'm bashing 45ACP or picking the GAP over it, as I'm not. The PA State Police are happy with their G37's, and I like it as it feels more comfy in my hand, as I do have small hands. The Florida Hiway Patrol is going with the new Gen 4 G37 GAP and should have them around March of this yr. That makes 5 State agencies using that platform. So in MHO, I think the GAP is here to stay. YMMV.
I hope this was helpful in some way.
Good luck and always stay safe.