Process ECN-2 specifies 3 alternative bleaches, two ferric nitrate and one ferricyanide. Cine Ektachrome processes usually specify a persulfate bleach, which requires a special accelerator prebath. I understand the accelerator has some affect on color and stability, too, but I may be wrong. Print films may use ferricyanide, Ferric-PDTA, or persulfate bleaches alternatively. Most home kits seem to be Ferric-EDTA or Ferric-PDTA. Obviously, you have some flexibility, but there may be a difference in the requirements for positive vs. negative film. Fixers vary a bit, too. They seem to be tailored to the bleach used, adjusting the pH as appropriate. Depending on the process, the fixer pH may be anywhere from 5.0 to 6.5. They are all non-hardening. Those for Ektachrome contain EDTA.

In looking at Kodak publication H24, which only applies to cine products, it is evident that the processes are designed as a system, and that the parts interact. Negative camera films seem to be the most tolerant of variations in the bleach and fixer, but even with them there are limits.