I have a Para-Ordnance P10.45, which was the predecessor to the Warthog. Some people reportedly had problems with the P10.45 so Para stopped production for a year or more, and when it came back it wore the "Warthog" name. Mine has been completely reliable. However, I haven't run tens of thousands of rounds through it. I bought it partially "just because," and partially to have a small pistol with 10-round capacity. I don't regularly use it as a range blaster.
My hands are average, not huge -- I generally wear a size large men's glove. My P10 has flush-base magazines and I don't find it especially difficult to grip for shooting. A friend, who works in the shop at the range where I shoot, has an actual Warthog. He also likes it very much. His magazines have a pinkie protrusion, which probably helps a bit with the grip. I think that's the only type magazine they've been using for several years.
Yes, ParaUSA has been absorbed by Remington.