The 500hp tail rotor trade off could be a bit of marketing hype, but the general rule of thumb for a conventional helicopters tail rotor is to draw 10 - 15% of total output. This isn't far from the mark although I believe the H60 tail rotor would be on the more efficient side of the 10-15% envelope.
I don't have any reference manuals with me at the moment but when I get back to work I can look into the average power of the tail rotor. You have aroused my curiosity.
Do those funky wings cancel out the effects of compressibilty or RBS, that spinning thing on top will still limit the VNE if I am thinking correctly. What are they really hoping for with this monster.