Have about 160 miles on mine now, and I like it. makes it a bit easier to initiate, not huge, but a bit. I don't notice it down a trail. Ride with other pros and some liked the change, some felt it made it to easy to tip and wash out. I would say if you love the way it is, leave it alone. I wanted it to be a bit easier to initiate for downhill turnouts etc and it is. I did wash out twice on steep sidehill with 8" of fluff and HARD snow under. stock sled washed out on it once also. so maybe a bit easier to wash out, but not much.
I would say any mod has plus and minus. most really aren't worth the cost. Buddies sled is bone stock. I have pro-motion, clutch kit, 3" track, triple rate springs - and not a lot of difference in performance. now in some snow conditions or in that one spot that the extra 1 mph track speed made a difference, it helped but not a big difference. That is the great thing about the pro, it is great stock.
all in all, I like the pro motion. My sled is a bit easier for me to maneuver and lay over and I didn't feel like it made it washout or unpredictable.