I've run both a 156 X3 on axys and now a 153 PC. The X3 digs way harder then stock, but still floats a little more then the powerclaw.
The powerclaw flat hooks up. thats it, it just digs and goes, this does result in a little less forgiveness and will dig and flip you over quicker if your not careful but also makes for a VERY VERY fun sled. Definately a more expensive combo to run the PC, but it is a rocking setup.
Also, note, if your in CO/UT/WY riding lighter fluffier snow the powerclaw doesnt shine quite as hard. Western MT, North ID, WA, OR, BC, AK etc with thicker snow it really shows its ability. It feels like some big HP gain because of how much more it hooks vs a 2.6
Also i would highly recommend a gear down either a kurts kit or if you want to go lower, TKI when stepping up to any of these options. They ahve a lot more traction and being geared to 95mph is a bit ridiculous and makes a lot of belt heat. Geared down and lots of traction makes for a rocking seutp.