You have to have the mainsheet at a slight leaning angle so it applies some compression on the boom to push the mast and keep it rotated. [/quote]

And by that I presume the designers anticipated that sort of load? I guess by switching to a 10:1 mainsheet, you're not actually increasing the load, just the amount of force needed by the crew to apply that load, correct?

I mean, "block to block" is X Newtons of force on the sail/boom, regardless of whether you use an 8:1 or 10:1 setup, right?

So, how do the boomless sails manage to keep the mast rotated?