some people will say that 1. 1/4 sch 40 is better (And cheaper) than HREW for slider/bumpers/ non structural parts
then there are the "pipe is for poop" people, then the "use nothing but chrome molly" people... the fact of the matter is. some pipe is strong enough to be used for a cage, its heavier by linear foot than HREW, dom hrew, and obviously CroMo. When compared to strength vs size.
dont know if that made since. sorta did to me
anyway, i was always in the pipe for non life saving use only crowd. Until i witnessed a fully pipe built roll cage in a toyota do an ass over flip and come out un-scathed.... not saying i would use it, but if built right pipe does seem to serve its purpose.
Strength is all relative. With a steel or iron pipe, you need a thicker wall, the higher strength steels, you can go thinner on the wall, have the same strength you need and have a lighter cage or bumper, thats the idea behind using chromolly or dom