I run an eq unit as well as the BBE. Without the BBE my setup sounds absolutely lack-luster (and I've tried various different EQ settings with both the EQ unit on and off). The rest of my setup is also in no means cheap or low-end, so its not the fault of the rest of the setup, but just due to the fact that the MP-1 to my ears does not sound all too great without the BBE.
The MP-1 to my ears is incredibley thin and has the bass frequency set way too high to be as effective as it should be (or for it to sound good, for that matter). The BBE helps to fix this issue however, adding a large amount of low end and general fullness to the overall sound, and I have zero problems with the mix when I use the BBE. In fact, my guitar sound in mix sounds a hell of a lot BETTER with the BBE.
Tweaking all the sliders on the EQ unit, with the BBE off, has not lead to results as satisfying as with the BBE on. Bass boosted, mids cut/mids boosted, highs tweaked, etc etc. everything you would typically do to help pull a better tone out of a thin setup just did not satisfy me as much as the BBE did. Honestly sometimes an EQ is just not the end-all to tonal problems.
The fact of the matter is most of the people who complain about the BBE and tell everyone to throw them out and "get a good eq" probably don't/haven't used the BBE correctly. It's supposed to be used subtly as a TOOL, not as an overall effect. Turning the process knob anywhere above the 9oclock position leads to a very processed, mid cut, tinny sound, and pulling the lo knob up above 2-3oclock leads to a bassy mess.
You need to work with the unit to find the correct settings that work with your unit... not sit back and complain that its a P.O.S when you cannot find the correct way to utilize it; subtly.
The BBE, contrary to popular belief, does not NEED to turn your tone into a processed mess. Using the unit SUBTLY with my VH patch leads to a very organic tone reminiscent of a genuine marshall head. Many people who complain about the ADA mainly say that you can tell that its a preamp, that it doesn't have 'the sound' that a real head does. I can agree with this statement... until I add in the BBE however.
...This is all person taste however... so you cannot take everything I say as 100% fact. However, this also means don't blindly listen to people spewing hate about the unit, especially those who overuse the effect (which many of the people who've complained about the unit have likely done).
Peace.
-Jarrod