Yeah but this shouldn't be an issue if your bender is setup properly. As long as you're not collapsing the tube, or flattening it out you shouldn't have any problems with strength. And for those who screw it up they probably shouldn't be building their own cages/frames anyhow.

Round tubing has the same strength in all directions whereas square or rectangular tubing does not. I worked for several years building tri-legged towers. They're always built with round tubing to withstand pressure and twisting from all directions as well as supporting several thousand pounds in compression.

 

Thats a valid point monster, but anything not done correctly is going to be weaker and have problems. I also agree that novices should probably stick to square stock. However, material strength for material strength, square stock can't touch round stock. I haven't really touched on the dom vs anything else points, simply because although pricey, dom is the only way to go for load bearing. You'd have to have a substantial increase in weight and wall of lesser stock to match Drawn Over Mandrels strength.