[bdeutsch]

Pound for pound, round tubing is stronger than square tubing. Of course, there are different ways to measure strength.

If you bend a square tube across the corners instead of across the flats, see what happens. Failure starts at the corners because the stress gets high there without supplying a lot of moment to take the load, because there isn't much material out there in the corner. So, if you know the orientation of the load, square is probably better. If not, or if there are many possible loads, then round is better.

Important thing to remember is that strength goes down rapidly with an increase in length ; by the square of the length in fact.

No desire to argue, suspect it comes down to a discussion of strength versus weight.