I have fired one and didnt care for it. Just simply dont see the need in it, or the risk involved. When I say risk involved, I mean that I already own several 45acp pistols, and dont want to risk inadvertantly loading a GAP round. I have enough issues digging a few GAP cases out of my 45ACP brass after I clean up at the range before reloading.
Also, with the SF models it tends to negate the frame size issue on glocks, at least in my opinion.