I haven't ridden them but I have a friend who has them. I haven't heard him complain about them buttering out so it must not be that bad. However, they do chatter quite a bit on groomers, but if you're buying Hellbents you're not buying them to be a groomer ski. Overall he absolutely loves them. I know this isn't all that much info but I hope it helps
I have hellbents, and they do chatter on piste, and are scary as fuck if you bomb any groomers, cause they are very slow edge to edge and you basically just ski on snow blades cause of the rocker. BUT I didnt buy hellbents for grooms, but for those awesome pow days, where they just destroy all the pillows. However these skis kinda suck for charging big lines and skiing tight trees, but for pillows, jumps, and just reeeeal deeeeeeeeeeeeep pow these are awesome!!!!!!!!
i really love mine, except for the fact that they are very heavy. laying down big archs i didnt find very difficult on groomers, also is going fast not too scary, as long as its a little softer i was never scared that the ski would do what i wanted. on ice it sucks but then again, who would ride the bents on ice? id say go for em.