My only concern is that PU works with dive (and scarab's swarm ability) in a strange way.
I'd say PU should make an exact copy of the card, that is if you PU a dived pegasus, you get a dived pegasus, and when you end your turn, both pegasi should have their attack dropped back.
The way it works right now, it takes the temporary attack and temporary hp and makes a creature with temporary stats based on those. But the copy is still missing some features of the original like the fact it is considered 'dived' for example. And Scarabs after being PUd probably behave as if the have never gained HP from their swarm ability. And that's the only thing I find strange and needing a change.
Maybe a change to that mechanic would weaken the dive+PU combo, but then adding a +6/+0 card would be more reasonable (and would bring the combo back to power).