Hi Wouter,
A 2.5inch by 6 inch mast would not do the job for me on the SC20. I did not survay the world for existing extrusions but I did survey the US and English and Italian mast extruders back in '78 and no one had a mast that would do the job except for some that weighed form 2 to 4 pounds per foot. The Tornado section, 3inches by 5.5 or 6.0 inches would not do the job. I broke three Tornado masts in three months, identical breaks. The extra 20% of boat width and double trapeze of the SC20 more than overloaded the popular Tornado mast at that time. The section you point out probably wouldn't stand up to two persons sitting on the windward hull of a 12ft wide boat and it certainly would not keep the boat from going turtle in case of a turnover. The section you suggest is academic trivia relative to the problem I chose to solve.
Bill