It appears that the BAD lever fell out of favor about as fast as it came in. I still have them on a bunch of guns, and am looking to add one to one gun that doesn't have it (I really missed not having one when shooting my PCC at a local action steel match a couple weeks ago). That got me wondering why they went away. Is it due to wider availability of ambi lowers and other devices? Is there a knockoff version that's "better"? is there something people found inherently wrong with them?
I think I was one of the first people to have a pre-productiong, pre-Magpul BAD direct from Travis (maybe not, I dunno) having gotten mine from him in March 2008 and maybe that makes me biased towards them? I think just about every AR I've spent any significant time with since then has had one on it.
pictures from the Magpul link above