The Pro has 3 major advantages that make up for a mild motor.
1. Clutching. Most efficient clutching period. I believe the Polaris loses the least amount of power from the motor to the track vs Cat and Ski Doo.
2. Suspension. This skid flat works. When the Pro hits the gas it gets on the snow and moves forward quickly. When the Cat hits the gas it digs down, trenches and then eventually starts to plain on the snow. By the time the Cat starts to get on the snow the Pro is gone.
3. Weight.
The Cat needs a skid that will transfer in the deep snow. In a situation where both sleds are track poaching trying to punch to the top of a steep hill the HP of the cat may show up and give it an advantage. But in the deep fluff the advantages of the Pro are tough to beat.
I ride a 2010 TM8 and a strong '09 M1000 that's light. I ride with a bunch of Pro's and in the deep powder my M1000 doesn't have any advantage unless we are track poaching trying to break a trail over a steep climb.
Give the cat a few years to loose some weight and get a Holz's rear skid and then it may close the gap in the fluff.
Looks like 2012 is going to be a repeat of 2011 with the Pro as the sled to beat. They flat work in the deep snow and are a hoot to ride. Gotta love good competition b/c we all win when the manufacturers compete.
Good thing I kept all my Polaris tools. After the mess from '06 to '10 I may have to jump on another Polaris. I've loved the time on the M's though. Super fun sled but the bar has risen again. (unless someone can put an 1000 cat engine into a Pro

)