In my experience/opinion, it depends on whether you are coating film, glass, or paper. Glyoxal is far better for paper, but it's a disaster with glass, unless your goal is emulsion transfer! Hardeners of any kind are by and large unnecessary for glass (if processing solutions and washing water temps are kept between 65F and 68F and all the same temperature, and you handle the plates with reasonable care.) I'm still deciding on film. Right now, I'm using a hardening stop bath (made with chrome alum) and hardening fixer. This is on 3M subbed film. I haven't noticed a problem on Dupont (Melinex) film or hand-subbed acetate, so...jury still out. I have been meaning to try grocery store canning alum in a stop bath, just to know. Is that available to you?