Do a google search for "wheel spacer failure " or "failed wheel spacer" - its not entirely a myth. I think the implication is that next to brake mod's, there's not really another mod that could be as catastophic under failure as a failing wheel spacer. The school of thought is that if you're going to do it, get good ones. Nobody is saying they're going to fail - but the point has been made by lots of people that when it comes to safety, why skimp on $80 for a set.
My question is what makes spider trax better???? You can also google hub failures and probably get just as many hits. I had a hub fail on a s10 blazer. all the lugs sheared off while doing 70 mph. No spacers were involved. I googled wheel spacer failure and all I see are forums with questions about spacers.
I'm not responding to just create argument. I hear too much internet rumors to believe everything. This is better than that but no one can provide any real proof. When peopl have failures you have to look at the true cause. Is it the spacer or something else. People say it puts more stress on bearing but it is no different than a wheel with different spacing.
From experience of over 100K miles with 35" tires and some very hard wheeling, my less expensive spacers have had zero problems.