It wasn't clear to me how closely you've looked at PgQ. Have you looked into the design (other than the README), or used it and found these failings? I'm certainly not going to be able to answer your questions off the top of my head given the time passed since I last used it.

Given your critiques of everything else out there (from what I gather from the rest of your comments in this thread), it seems like your identified a possible business opportunity.