I've ran both, and havent noticed any negatives really. Not much for trail riding around here, so i cant judge too much on that. Honestly, the M practically falls over for sidehilling and stuff, that i dont think i really even noticed a difference there. It does help cut down on the amount of snow that hangs out in the skid, and looks pretty cool, so what the hell. I wouldnt buy a kit though. With the right sized tap, and a couple heavyduty washers, you can whip up one in your shop while sipping on a hot rum, or beer, spending no money. Did that on my M7, woulda done it to my new sled but she came like that. Its easy, giver hell!
Brian