I would recommend waiting to buy the fvb3 pedal. I bought it to use with my mkii amps and there were so many issues. I spoke directly to a line 6 tech and he told me that they are working on new firmware for the pedal which should fix the bugs. I believe this will be a good pedal after the update. For now, I'll stick to the mkii short board .
I got 2 of these and neither have worked with my mkii. The volume doesn't turn off completely. The tuner will not work. It takes forever to switch through channels. What am I doing wrong? I've waited for this pedal for a while and I'm so disappointed