I do prefer hard pads. But if any sander didn't have a hard pad option the pro5 would be the one. The hard pads excel with use of more powerful sanders or larger sanders that can cover a lot of ground for flattening.
I dont see the hard pad saving much time over the regular pad as anything I really want that hard pad for I wouldn't be choosing the Pro5 in the first place. So I get why they dont offer one for it. I would probably buy it though, I use use hard pads on all my sanders that offer one.
My Pro 5 don't hop around at all, but for the guys that have Pro 5s' that do hop a hard pad is just going to make the gouging worse.