My point was not "pop" rivets as in "pop rivets" that was simply an (as it turns out) oversimplification Darryn as you have noted, the main point being that it is unwise to weld aluminium when it is to be used under flex and stress loads. The Mozzie uses rectangular beams, as you are obviously aware, and although your points of ease of use etc are valid, they have, and still regularly do get more than their fair share of failures when compared to cats with round sections (or mast "pear" shaped)
Any way all the best and good luck next week at Christies Beach