Using a Bbe during live or band situation is not effective in many cases. However if you are playing old recordings and know how to use one to tailor for room acoustics they are an absolute necessity.
I tire of these posts "Well I tried one once and it totally screwed up the sound"
It is a another tool that works if you know how to use it.......
Some also knock the Aphex Here is another
link
It is old but note the referene to the 102 in the 4th paragraph..