Good comments here.
Noticed you said Fanatic Blast. I'm definitely not an expert sailor, somewhere in low intermediate, and I have a 145 Blast and a 11'8" exocet and it looks similar in outline but is a lot heavier and has a daggerboard. My main complaint with that board is the weight. I enjoy foiling but I also do enjoy getting my longboard planing. It takes more than a shortboard but the exocet pushes through the disorganized chop way better than the Blast does after I upgraded fins. It came with a 34cm (I think) pretty blunt fin but I run a 40cm k4 fang and it does well. As Awalkspoiled mentioned, you could go even bigger. Someone told me they go with a 44cm carbon fin and really enjoy it.
With that fin, and without using the daggerboard, going upwind is not a problem. The daggerboard did help a lot in subplaning conditions but even so I don't have a problem taking a board that big and floaty out on a trip.
If it is built by exocet I did have some problems with the footstrap plugs stripping. I've yet to fix it but I will eventually when I have more room to do so.
Subplaning with 9.5:
Overpowered in gusts with a 7.5. I could've been on the Blast but it beats me up a lot more in this kind of chop than the exocet does: