GNCC and XC racers have been using these for 6 or 7 years now with success. Like mentioned, the dual setup has problems with packing up with mud and stuff, but someone(not a company, but some dude online) has made a small little brush system that he calls 'the guard dog" that cleans out the dual guard setup. You can get the Guard Dog brushes through GT-Thunder. LoneStar sells single stainless steel guards, all of the dual guards are aluminum, dual stainless guards are a lot of heavy rotating mass. I've heard that the design of some of the newer the dual guard are vented to allow debris to exit easier, so drill some holes/cut some slots in the design.