Quick bit of research on the Bass Fly Rig v2 shows the differences are as follows:
• A choice of SansAmp Character modes:
SansAmp Bass Driver DI for a variety of classic bass tube amp tones, or VT Bass DI with a more specific focus on Ampeg-style tones.
• Channel switching for two different Drive and Level settings.
Go from clean to dirty, not-so-clean to not-so-dirty, very dirty to downright nasty, or any variation in between.
• Effect loop to facilitate incorporating additional outboard effects.
So the v2 definitely has more utility but the Sansamp part of the v1 rig I am selling is still a Sansamp! So you can get fat tube, SVT etc sounds out of it