As you can see by the avatar our Blaster loves to fly.
2" stud spacers all round on a Banshee rear axle and widening kit on the front end.
Running MX for nearly 2 years with no problems, not a sign of breakage or pronounced bump steer.
I would consider removing them if anyone posts that they have broken one and the details of how and why.
It seems to me this topic is somewhat like the DG pipe senario, everyone says they are crap, but have never seen or tried one.
They seem to be extremly strong, there was an occasion when our pit mechanic forgot the tighten the lug nuts on a rear wheel.
After the Moto had finished the problem was noticed and the holes in the wheel were chewed up beyond repair but the spacers were unmarked and working until this day.