My replacement ESC from Castle Creations (the Phoenix HV-110A) finally arrived today, along with a Castle Creations USB programmer for it. The Phoenix HV-110A is considerably beefier than the ELF controller that I burned out. I reprogrammed the Phoenix using the very nice USB programmer (notably: BRAKING off) and installed it onto my Piaggio.
If you have the right QuickTime codec installed, you can watch a very boring video of my biking revving up to speed.