I have a bass with a Bart 3 band, and find that I like the mid boost quite a lot (I generally have lows and highs flat, mids slightly boosted). I have another bass with a Bart 2 band, and ... so I leave it pretty much flat. I feel like a lot is missing without that mid control. If you have and like a 2 band, what do you like about it, what kind of bass is it on, and what kind of sound are you going for?
I have a Glockenklang pre-amp 2 band (Bass, Treble, Blend). The bass I have has a natural midrange response to it and I don't feel I even need a mid boost knob. I usually only increase the treble and that's rare. I don't touch the bass knob on the Glock, I just adjust on the amp. Active pre's give a stronger signal through a 20 foot cable than a purely passive system - from my experience...I may be wrong. Plus the clean tone from the Glock is easy to work with. Spector Euro 5 string with Padauk wood
I have a Spector NS4CRFM with EMG P/J pickups and a 2-band EMG BTS eq system. I find the P/J setup has adequate mids and highs, so I only boost it's low end for certain sounds. I agree with you on 3-band eq's, I like being able to boost my mids. I find it makes my bass more audible in live situations. I've also noticed the Bartolini pickups that I've used have an inherent low-mids hump which adds a punch to my sound. For me, Bart pickups really through the mix, yet blend well with the rest of the band.