Dumont's double is actually really easy, but he supermanned like maaaaaad lol. But I've seen footy of PK doing it as well as a whole host of other pros.
Best trick as it stands right now is probably true double cork in the pipe, DJ flip, or PK's Switch double 12.
I also give credit to Bushfield for having the balls necessary to do that massive switch double backflip on the Whistler booter a few years back.