My advice is (I see you Toni and you have started the discussion already, great!):
1) Don't make a driver, make a floppy read/write app
2) Make it the deluxe, 100% reliable, workhorse file<->floppy solution first. Don't add stuff not related to writing floppies in a better way
3) Make it open source and port the app to every OS known to mankind !! (Mainly, the different Windoze flavors I guess...)
4) Make it dirt cheap. Expect Amiga users to want it for < 25€... Impossible of course, me, I'd pay 100€ for a perfect plug-in solution rather than a free PCB layout and buying components for 45€ from 5 different places...