Just curious - I saw some of the web browsers for Amiga can take advantage of the FPU. Not that web browsing will ever be amazing on a classic Amiga, but perhaps that's a use case if you have need for occasional web usage? (i.e. NetSurf)
Also if you're (for some reason) emulating a classic Mac on the Amiga, I think the MacOS really likes to have the FPU.
That said I'm not encouraging the risk of adding the FPU to that accelerator :).