Hey Track,
It sounds like you've already received a lot of good input. Perhaps with my 2 cents you'll have enough for the epoxy?
Now that I've had experience with both methods, I can say unequivocally that the hull build phase is way faster with S&G. The strength and quality can be equal, if built to be so. In other words, there're no inate greater strength to frame designs over monococ designs.
I believe that cost would also be lower. Granted, the S&G hull calls for more epoxy, filler and fiberglass, but you can dispense with the screws and lumber.
The deck and finishing will require the same effort, all things being equal.
As for adjusting size a few inches here and there, this is where S&G is brilliant, because you can make those sorts of amendments easily when cutting the materials. Not so easy with frame designs. In the tug that I'm building, for instance, I've thought that it would be convenient for certain applications if the beam were reduced by as much as 9 inches. This would be very simple to do during the build, by reducing the width of the bottom plywood cut at the start.
Whichever way you go, I hope it'll be fun as well as profitable.
Cheers,
Richard