So I got a GT-6B. I was expecting a lot out of it, since I have a GT-3 and GT-6 for guitar. I'm still trying to program patches (as usual, the presets suck), but here's my take on it. The board set up is different from the guitar units, but I think that's a good thing. It is set up like the Digitech BP8, where pedals can turn on/off effects for each patch. The worst thing about the unit is the compressor effects. Only four models to chose from, and programming parameters is "hit and miss" due to no way to monitor compression and level (no meter -- not even a LED). You'll have to set it up with something that can give you an idea of your level, but you are still guessing when the compression kicks in. I've been doing it by ear comparing to the bypass. Over all, the unit's compression is not up to par. Too bad as some other effects are good. Again, as usual, there are many effects I'll never use. Just not meant for bass, and are likely just a carry over from the guitar. What I do like are the octabass, the EQ, the amp/speaker modelling and the chorus. Haven't decided on the the defretter effect (which to me isn't really a fretless effect, more of an attack filter), the envelope filter, and the harmonizer effects. Don't like the flanger, phaser, pitch bend (whammy), and other effects I probably won't use on bass (reverb/delay). It would be a great value if Boss would upgrade the compressor section, but "as is" is marginally effective. Can't recommend as a "must buy".