Hi Brian,
When I first got my Azo, I was waiting on the delivery of Amidol, and, as usual, had no patience to wait it out. I had often read that Agfa Neutol WA was an alternative to Amidol, so I pick up a bottle. It was certainly more economical than Amidol, but that is where the advantages over Amidol came to a screeching halt. It was only after receiving my Amidol and making the first prints that I was able to see how clearly superior Amidol (either the Michael Smith or the Peckhams Amidol/Catchetol) really is. I only wish I was able to get back the 30 or 40 sheets of Azo that I literally wasted by using the Agfa developer.
Are there other developers out there that can be used with Azo? Probably. Are they going to get the most out of the paper the way Amidol does? Probably not.