I use that BBE unit with a PA every weekend. I think it works great in that application. It "clears" up the mix pretty nicely. When I use a house system without it, I miss it. It's simple to use and unless you have the worlds greatest PA system, you won't be able to hear what most people seem to not like about it. In the studio, at first listen it seems to sound better, but then you start to notice a "processed" quality to the sound that's a bit unnatural sounding. But live at 100db+ through an average PA system it makes a real positive difference.
I have it hooked up using insert cables on the main buss of a 2000watt carvin system. If you want it for PA, IMHO definately get it... for studio--avoid at all costs.