I run spacers and ride as hard as anyone I know and havent had a problem with them yet.... I love the feel of a wider bike, they have been through about 2 1/2 months of abuse so far, rocks, sand, mud, ect and have held up absolutly solid, I would recomend them for someone thats wants to widen there quad but doesnt have the extra $$.... I will probably switch to an extended axel this summer when im making a little more $$ but for now its a solid buy.
btw im running the g-force spacers, deff better quality than most