The thing is my observations are based on total experience. I had one of the first hardware units when they first came out. Had several since including software. I was seduced by the whole concept like many of us. I used it on mixes, used it live, tried it everywhere.
But after some careful listening I found I preferred the sound of anything without it. I found it was totally unnecessary, especially live. I have a lot of live experience, probably much more than most. The live sound you get is very dependent on how you set up your PA and tune it to the room. I don't even use pink noise much these days to tune PA's, although it can be helpful at times. I find all you need is a great reference CD. I use Steely Dan's 'Everything Must Go' as my ref. I know it very well and it how it is meant to sound on expensive monitors. I just adjust the FOH EQ until I hear what it should sound like and that is it. From that point on the PA sounds perfect. Perfect bottom and top end. No need for any boxes such as this. It just takes skill that is all in setting up your FOH EQ.
I mix on large systems that are built into venues here in Melbourne. When I come in to set up I often encounter a ridiculous FOH EQ from the idiot the previous night. Looks like a dogs hind leg. Put on Steely Dan, sounds like crap usually. What is funny is that when I set the FOH EQ completely flat Steely Dan often sounds very close to perfect.
(Well done to the guys who installed it and lined it up) Only have to tweak subs
(they are often just too loud but easily controlled and put back in their place) and one or two faders at most to get the perfect FOH sound out front. Then after doing a killer mix all night the bar people and venue owners come up to me and say they have never heard the PA sounding that good ever! That is using my ears my friend and nothing else. NO BBE boxes involved there either. So it shows clearly they are not needed, just lots of ear skill that is all.
I also use Steely Dan to tune the foldback system and then just roll off the highs above about 7K to stop any HF squeal feedback and then the musicans tell me they have never heard the FB system sounding so good as well.