Question is wether the 6.2% difference in mid girth (SMG) dicate a different shape to Tornado spis as compared to F-16 and F-18 spis.

I dont know, and if we could get some definitive answers at all from e.g. Gran, Landenberger, E.P (Harry Pattison), Glaser e.a. about what constitutes a fast spi I would be really thrilled. It seems like the big sailmakers dont go public with their knowlegde about fast catamaran spis, but perhaps they share some with good customers. For mainsails and jibs the 'fast' parameters are well known.
I can speculate tough, and I would think the 6.2% difference in girth not enough to dictate a radically different shape. I know Gran Segel have made some F-18 spis with success. But penetration into the F-18 class is harder than the open Tornado class as the best teams usually are bound to specific gear by sponsor agreements. In my opinion, the important part about the leech is that it should not backwind the mainsail. Getting the balance between a open leech and well setting luff is hard, especially if you want the spi to be easy to trim and fast in different windspeeds. I am looking quite hard into the topic right now (from an amateurs viewpoint), and it's quite hard to get right.