"Adding EDTA to the developer": I have never heard of that. EDTA is fairly safe (it is a food additive), but I would be interested on why it would be considered a hazard. You used Hypo Clearing Agent -- if you used Kodak's, I believe it has some in it. But just about any platinum printer will eventually come up with their own clearing routine. I use a citric acid first bath, followed by two baths of HCA (or Sodium sulfite) and EDTA.

From what I understand about digital negatives (which would not fill a thimble), one of their strong points is by standardizing one's coating mixture, paper and processing steps, you then only need to make changes in the digital negative to match what you see on your monitor...unless one wishes to change print color and/or paper. Then one would test and create a new profile (if that is the proper word) for printing the negative with the new paper, etc). Not really different than the way I work -- I attempt to expose and develop the negatives to print without any contrast agent in the coating solution or developer.

You can get rich prints with Ammonium citrate -- you would just have to test and change your printing profile to match the developer. But the color will be different than Potassium oxalate. Again, congrats on a great workshop and excellent prints!