Interesting thought. To make things even more messy I actually have an Aero 127 which I use mostly with my 6.5. The AE is a lovely board to throw around in chop or waves and it jibes excellently. Itīs just not really speedy and the outside strap position is a little too upright for me. Itīs a sort of out of context board but I really like it for playing around.
I love the St115 and I also use it with the straps inboard if I want to play a little with chop or jump it. With the straps in the outboard position itīs a very aggressive speedster. The isonic 111 would probably carry my 8.5 nicely and plane just as early as the Aero, but I wouldnīt switch my ST115 with it...
Futura 122 looks very interesting indeed. Maybe it could actually replace both my Aero and my St115, at least until the wind gets above 30 knots where I use the St with a 4.7 wave sail successfully. The Futra 122 has good strap positions for both speed and manouvers.
Liveīs hard when you have fun ;-)