Yeah, I've dropped a few pubs. Some pubs are just vanity projects for their owners. It makes sense to cull those memberships.
I try to keep the ones that are really supportive. I'm close to dropping Illumination because 1) the last two things I submitted there went weeks without acceptance; 2) it's just so much with little apparent quality control; and 3) there is little discernible reciprocation. I think the Illumination pubs have just gotten so massive they have ceased to be efficacious. And, I've found the BBB and BBP pubs which is much more responsive and reciprocal than any of the other pubs in which I'm listed as a writer.