Thanks! As for "proper" sails, I don't know, but my sail is being made new for me. I had contemplated trying to fit a Nacra 20 main, which is nominally 18 sq metres in area.

I have not sailed yet with this mast. However, my old Nacra 5.O had the non-captive early Nacra mast base system, with the open hemisphere and the small ball. For safety I'd always tie a short line from the mast base to the striker while stepping the mast. This T mast has a similar step, and likewise, I tied a small line to it to keep it from falling completely free if it slips off the step ball while it's being stepped. It has worked fine while rigging it, but I haven't sailed with this mast yet.