Basically the 6 step process gives you more control than the 3 step in that with the latter--certain steps are consolidated for simplicity. Almost all of the corrective actions in E6 apply to the replenished 6 step process. With one-shot 6 step E6--you can do some slight corrections mostly with pH and specific gravity that might be needed for certain types of processing such as continuous rotary tube agitation etc. The 3 step kits might be the easiest overall to use, but they would offer the least amount of control.
Originally Posted by Jan Brittenson
As for longevity? When most of the manufacturers ditched the formaldehyde based stabilizers---they went over to a Final Rinse that is very much like a wetting agent more or less. In the "new" Kodak E6--the stabilization part takes place in the Pre-Bleach and is triggered by carryover color developer. In some types of reversal processing--old Kodak E6, Fuji CR56 (unless it's been changed??)--they still use a stabilizer, and there's a wash in between CD and Conditioner (which has been eliminated from the current Kodak E6)...so--this is probably overly confusing, but there *are* differences.
As for the color biasing of Kodak & Fuji? You *should* be able to run any type of chrome film together, just as you *should* be able to use the same First Developer time. The point of E6 is to try for a standard process--although this is a moot point if you only process one type of film for yourself. Personally I would suggest trying to do a standard process as best you can & try to make it as routine as possible--i.e. the same way every time.
Where I work, we process mostly Fuji with some Kodak--and use a std. First dev. time based off control strips using one-shot Kodak 6 step E6. I've read the claim by Jobo that Fuji needs extra time--and this makes no sense whatsoever to me--because you should adjust the film speed accordingly back against a standard process. The Fuji version of the Kodak Q Lab is called an Oasis lab. The Oasis labs use Kodak made control strips in Fuji CR56 chemistry. My point is--it doesn't matter what film you run--the process is the same.
HOWEVER---Fuji films will shift on agreen-magenta bias depending on Color Dev pH and Kodak will run yellow-blue. you can adjust the pH by adding either sulfuric acid or sodium hydroxide to the CD in small amounts to correct. As was mentioned above--water quality is a big factor, but if you mix & store your E6, be aware that CD pH can drift as it sits--it usually becomes more acidic.
hope this helps--