Even with my 8:1 mainsheet, when fully tensioned, the boom displayed an annoying upward flex in it. I can only imagine what the 10:1 blocks will do.

Is there any particular reason that the sheet point is behind the clew of the main? Does it help keep the roach/square top tight?

Having it that far back certainly seems to stress the boom moreso than I would have thought. But I guess that's part of the design, too...?