I just found out that the new C4 adjustable will be about $225..(I'm guessing/hoping that's Aussie dollars)...also max length is 83"...

I don't see how the handle shape could effect downwinders, upwinders, or even waveriding...It would be just a matter of getting used to it..I guess.
I'd like to try it...I've heard that your top hand should be relaxed and with almost open fingers..so you are almost 'palming it' as you push forward.
This new design might help with this technique.
It looks like shops that sell C4's will have this paddle available for those people buying a C4 paddle..so they can demo it and work out what length is best for them..so the shop can cut their new carbon paddle to the right length for them.
Sounds good.
btw..There's also a alloy/fiberglass C4 for about $200...Both available about mid March 08.
DJ