Got a Sansamp TriAC a couple of weeks ago and I absolutely love this pedal. I played through a BDDI and was less than impressed. Sure it was a cool little pedal, but didn't quite give me the tone I craved. It made my low end a bit too boomy for my tastes.
I bought a used TriAC online for something around $110 and it does everything I need. I have a "clean" channel that I use most of the time, and a channel for when I need that grindy, ballsy, in-your-face tone.
Another thing I love about the TriAC is that even though it's voiced for guitar, there is NO loss of low end. And I couldn't really care less about the eq voicings on the pedal since I have one on my amp and a 2-band active one on my bass.
One advantage I think people overlook on the three channel pedals is that you can move the knobs, then just press the channel to go back to your settings. From what I hear the BDDI knobs are very sensitive and interactive, and should you bump something mid-song, its nice to have your settings at your feet instead of bending down to turn knobs on the BDDI.
Just my 2 cents.