I tried a set of slp powder pros on my srx 2 years ago. They sent me flying off my sled a couple times and damn near broke my wrist! The problem was when I was boondocking across fields in 1-1 1/2 feet of snow that had a crust on top of it. The ski would break through and I think because of the deep keel it would dig in and jerk the handle bars to that side. I actually bent and twisted my handlebars trying to hold on, it was pretty dangerous to ride. I think it has something to do with there being so much weight on the front of the srx because my cousin has them on his AC crossfire and they work good for him.
I don't know what they would be like for trail riding but I highly recommend staying away from them for boondocking in deeper snow. I have a set of ski's from a 2008 nytro on it now and it handles great. The only time I'll ever use those powder pros again is when I go to the mountains for riding in the soft powdery stuff.