I recently picked up a 2010 NS Evo-r with the RC design. It is a rocker between the bindings but cambers on the tips. I only have one 4 hour session on this board but will share my thoughts.
First off, it definitely doesn't catch an edge as easy. Is this a good thing...jury's still out. Basically, if you are riding on flat ground, you can swivel your hips to turn the board back and fourth without any edge catching. This is possible because the tips are generally off the snow and only the middle is touching.
---Where I see that to be a problem is on landings. If you land a jump, sometimes you want that edge to dig in a bit to stabilize your the rest of your body. If you land balanced, it should not be a problem.
I've never had a soft board before but this one is definitey easy to butter. It also hops amazingly well. Maybe that is unique to this board (and not all rockers) but I can ollie off bumps higher than ever before.
As for edge grab, I only had a problem on the heel side. Maybe I wasn't putting enough pressure on it but sometimes it wouldn't grab on the tips. When carving at speed, the toe edge REALLY wanted to grab. Instead of quick cuts, it wanted to send me off in another direction. These are all most likely related to me being a novice on this technology. I might have an entirely differnet opinion after putting a few more hours on this new board.
Hope it helps or at least creates dialoge.