The rebound energy of the PowerAxe SL race plate is significantly greater than the Pe2 binding. I've skied both on 176 Salomon Equipe 10 3Vs made the same year and the difference is huge. With the Pe2 binding the ski is pretty easy to manage and feel very much like a narrow all mountain with improved edge hold. With the SL race plate the 3V will kick you out of a turn with emphasis any time you come close to using the tail at the end of the turn. The race plate also improves the feel and sensitivity of the ski. I find it easier to choose the point to initiate a turn with the race plate than with the Pe2. The downside to the race plate is that it can make the ski demand your full attention all the time. The 3V with the race plate requires more precise skiing in slop and crud or through transitions than the ski with the Pe2 system.
FWIW, I've also skied the same 3V with a non-Pe demo binding. I'll say that the Pe2 does add rebound to the ski as well - particularly in the tail.