So I just measured a CG fusion battle mistress with standard flat (non magnum) scales, and the over all circumference is basically the same as the nano fusion handle. 4.25 at the palm swell and 3.5 at the thin part above. The Nano Fusion is more contoured feels a little smaller but probably is the same amount of material over all. It is comfortable in my medium hands. Great handle and is a perfect example of why Jerry is so good.
As a reference point the middle of my NMFSH with Magnums is 4.75 (which is also comfortable to me) and Boss Jack with standard flats is 3.5.... Now I'm going to stop measuring the circumference of things