I have the Futura 133 this year, and I've sailed it with a 9.5 m2 Sailworks Retro with
I found the wider Futura 155 (85.0 cm vs 76.0 cm for the F 133) planes earlier/works better with the 9.5 m2, but the F 155 would be too similar to your Free Formula 157.
You will get quite a bit better "over the chop" performance with the F 133 vs the FF-157.
So, with the Futura 133 and FF-157 you will increase your range quite a bit.
I wonder at your question about the Futura 133 and your 9.5 m2 sail?
If you are indeed going for a 2 board quiver, I'd suggest the 9.5 will work better on the FF-157 and use your 7.5 and smaller rigs on the Futura 133.
If you were looking for a one board solution to replace your Free Formula 157 then the 133 would be a very good choice, but if you use the 9.5 most of the time, then the Futura 144 (77.5 cm wide) would probably be a better choice.
If you are looking to really extend your range, at 80 Kg. in fresh water, perhaps the Futura 122 and your FF-157 would be a better combination giving you a board that's really at it's optimum on a 7.5 m2 rig (the Futura 122) and your larger wider Free Formula 157 for light wind days and your 9.5 m2 rig.
You have a bit of a gap in your sail quiver with 7.5 to 9.5.
Hope this helps,