I'll throw out one more opinion.

They're really not that different than round bars, and carbon ones certainly aren't worth the money. That said, the FSA K Wing I'm currently using has a nifty little groove behind the hoods that fit my hands perfectly (other K Wing users know what I'm sayin!). IMO, that nifty little groove isn't worth $200 though.

Probably the best thing about a wing is that you can rest your forearms on the tops a lot more comfortably than on a round bar. Probably the worst thing is that they feel a bit awkward when climbing on the tops. Maybe a minimal performance advantage on solo breaks, irrelevent for anything else.

I can't compare an ergo to a traditional drop bar, as I've never used a traditional one. I'd imagine the difference is minimal, and it'd be easy to get used to.