Amen Fred!

Look guys, the C41 film family consists of over 10 layers with 3 sets of 3 emulsions making for a total of 9 emulsion types in each film. They all have to reach the right point at the right time or 3' 15" at 100F. Any change to that will cause problems (within limits of about 15" for push or pull). In fact, it is so critical that it is better to over and under expose than it is to push or pull.

And, correct processing is also a diffusion controlled process involving the color correcting chemicals which must diffuse properly to give the correct colors.

By comparison, B&W is a snap. Oh, and even in B&W a divided developer must be fined tuned for time and formulation for your particular film!

Anyhow, the guy in the reference from the OP posted the most difficult pictures to judge for crossover. For example, a portrait might have had greenish highlights and beefy higher density areas. BTDT. Anyhow, Pat Dignan and I exchanged letters on that in the '90s and we even talked on the phone. By the end, I think that I had him convinced that the divided developer idea might be a bad one. IDK for sure.

So, in a word, don't do it. Do it the right way.

PE