I agree with you that the .20FS would have been a better match for that airframe. I have an old OS .19 steel fin with an articulating baffle that I wanted to use, but this thing built out way too tail heavy. with the .19 or .20 on the front and the battery pack up against the firewall, I still needed a ton of lead to make it balance right.
The .32SX is not an ideal match to the airframe, but it helped me get the CG right without any lead and it idles really well, so it works out okay. Hand launches are a joke with this setup. I'm running a 10x4 prop and I can just about point it straight up and let it go.
The next one I build will probably get a 2" extension to the nose.