ya I much better like the idea of offsetting the frame and 'inserting' the drywall. I just suspect there are some people who might want to do it their way, but oh well, they can use a different system!

the extra layer of plywood is my biggest concern, I know it is going to up things quite a bit. the biggest reason it is there however is for shear strength.

Being isolated by insulation on both sides, it wouldn't need to be very high quality stuff, or overly thick. You could get away with 3/8" cheap plywood without any trouble, or maybe even rigid foam board would work (as well as add r-value). It's never going to get rained on, so warping isn't at all a concern, not to mention that it is nailed to a stud every foot.