Agreed. The ARB rails are only something like .095" wall tubing. IMO, .120" wall is absolute minimum for a slider and .188" would be better (but custom most likely as I know of no company offering that thickness).
Uphill's ARBs got pretty dented and banged up on Martinez Canyon here in AZ. Personally, I'd go with another brand.
I bought the ARB rails and they were damaged in shipping (They looked to be dropped on end and creased the edges of both sliders). Good thing they were damaged too, it gave me good reason to return them. I am fairly certain they would dent/crease the first time I tried to actually slide across something. The other things I didn't like is that they are a good 2 inches in width: reducing clearance. It surprised me that they were ARB because they usually make good stuff.