Mast-to rotate or not to rotate

[delevi]

So here is an interesting question. Roger claims that the rotating spar increases the sail's dirve and reduces heel. As for added drive, this makes sence, because it makes more of the sail usable. My question is about heel. I wonder if pinning the mast, thus keeping it from rotating, will effectively reduce a bit of sail area, and thus reduce heel in heavier winds. This is where I get confused, since Roger claims the rotating spar will decrease heel, but since it effectively adds sail area, I just don't see it, unless it alters the angle of attack around the luff.

[DLT]

The idea is that the lift vector of the sail is oriented more forwardly, rather than to the side.

http://www.macgregor26.com/sailing.htm