Boards - concave vs rails/channels

Looking at picking up a new board shortly...

Can someone tell the differences between performance? I see some brands sticking with the standard concave formula and others embracing the new technology.

Is it a gimmick to sell more boards or a progression in our sport?

Thanks in advance

Well not really fashion, these choices come from our big brother wakeboarding, the biggest difference between a kite and wake board is the concave.

The choice is more do you do wakestyle - get a board with as much concave for pop (but not as much as a true wakeboard so you can plane easy), channels, moulded fins etc for sliders blah blah blah

Or do you prefer getting out in lighter winds, cruisin, doing big jumps you better off with a flatter concave for easy planing - dont really need moulded fins cuz you dont hit sliders.

Its more or less a trade off between having a flat board which is best for speed
Concave which is best for pop - but stops the board planning faster
Fins which give the board direction - good for beginners, but fins create drag and in wakestyle you only want a small amount of direction from fins for more intense tricks - thus the moulded fins - they are small enough to still be used on sliders etc.

Oh yeah woops - was half asleeep - change concave for rocker in my post :S

Rocker effects pop sorry to confuse anyone in my first post...
Concaves create lift and make the kiteboard sit higher in the water. Ever so simply, concaves in different areas of the kiteboard created lift in different areas of the board. For instance, a double concave in the middle and a single concave in the tip and tail keep the board riding higher in the water overall. A double concave in the middle will always sit higher than the single concave.