Well, to be honest, the problems I have heard about are just that, problems I have only heard about. But here is what I heard, and who knows, could be a problem with the 38's and 39's as well.
Locking blocks cracking
Missfeeds due to the slightest limp rist. (this should not be a prob for me, I've got a number of 1911's and have never had a prob even with the Officers)
The elusive Kaboom
I hear what you are saying about the GAP and the ACP. I have a number of 45 ACP's and I reload. Practice ammo should not be as big of a problem. But carry ammo is a good point.
The thing that appeals to me about the 38 is the 19 pistol size with 8 rounds of 45 cal ammo. To be honest, if I could get my hand around a 30 or a 21, I would prob already own a USP compact. Right now I can swing the pistol and a good rig for it. I can not afford to pick up something I can't use. Maybe the 36 is the right answer.