I believe that with PAD, since it is winner take all, this is the reason why play is much tighter, even more so than in a normal tourney which would pay out several places.
As far as High Stakes, I would be very disappointed to learn that the pros are playing with 'borrowed' money, as it would not be a true gauge of their play. It would be meaningless, other than some entertainment value to the viewer, and the raw emotion of of the ups and downs of the game would be muted. You might also see some bad play from a person who ordinarily would not make it if it were to mean something to them such as losing there own cash, much like a loose player in a freeroll. So in that regard, it would teach a viewer bad habits as well. I guess the only real way to find out would be to ask a pro who plays on High Stakes. Anybody know one?