All of the Rocker boards ride pretty good in powder. Some are better than others. Like the K2 Gyrator, probably the best powder rocker out there. You ride it center stance, and you do have to keep your weight centered or you can easily get dumped. Overall a fun, loosey, goosey ride.
The Burton Hero was a fun board though it's fairly light and gets to chattering at higher speeds fairly easily. I am also not a fan of the ICS system. Too many weak points and I have already seen plenty of complaints about the bindings starting to shift after about 20 days on it. No matter how hard it's cranked down, it still moves around.
The Neversummer SL-R was a very fun board. With their Recurve tech the board is very stable at speeds and has all the fun of a rocker board. I found it a lot more lively than the Legacy-R which is the wide model of the SL.
The K2 Turbo Dream was a blast. Fun and playful, good at speeds. Same thing for the Capita Horrorscope. Those two boards were probably the most fun rockers I demo'd.
I took out a couple of Lib Tech's, the Lando and Rice, they were decent. Magne works to a degree, I don't find it revolutionary. The Banana rocker is a bit different then others, flat between the bindings.
If you are thinking that you will be charging big lines with fall and you'll get jacked up consequences, I would look at the Neversummer or Lib Tech models (except the banana that things a noodle). For park riding with good freeride capabilities, I like the Capita and K2 models. None of the rocker boards are going to be very great for Pipe riding.