Sounds like a good setup. Others have gone 50,000 miles on similar dual-tank systems w/o problems. Have you been to biodiesel.infopop.cc, the SVO forum?
Lots of F-250 conversions there.

The only F-250 problems I've read about has been rubber deterioration in the fuel cutoff solenoid in the fip, and one user who ruined two lift pumps. They seized when he switched to hot wvo.