What about a 4inch f/5 flatfield APO then?
Here is an interesting one:
http://www.teleskop-express.de/shop/...Telescope.html
Theoretically a plug n play, fast, and TS guys could for sure make an adapter for your QSI. Nice wide field with KAF8300, and resolution can be easily increased with drizzle integration to about 1arcsec pp if needed.