RE: Wind range for Isonic 145
I say that would be a really super combination!
I've sailed the Isonic 145 with both of these sail sizes and it rips!
The 7.5 is getting down near the bottom of the Is 145's best range, but if you lean out your sail a bit and get the mast foot and fin size right, it very quick, without being difficult to control.
Sort of like a faster formula board.
Hope this helps,