I tend not to place myself in positions where I might have to shoot upsidedown.

But I have both. I've never had a problem with PF. On the other hand, I've been annoyed a couple of times when my CRF varmint rifle faced one more vicious prairie dog than the magazine had rounds to service.

Now, floorplates on the other hand ... nothing's more exasperating than working the bolt over an open magazine. Well, except for snagging the lever on a No. 1 and ejecting a round into two feet of fresh snow somewhere.