Quote Originally Posted by Photo Engineer
The bottom line is that the formulas are only close approximations for E6, and will give only close approximations to specifications when used with most E6 films. The problem is that unless you do numeric or side by side comparisons, you cannot be sure of your results, only that they are 'satisfactory to you'.
The "satisfactory to you" test is the only one that's important to a typical hobbyist, though. The elaborate tests to get everything quantitatively "correct" are important for a commercial product, but home-brew formulas are, by definition, not commercial products. Being "correct" (which I read to mean "identical to Kodak's formula") is just irrelevant for the people who'd be likely to use color chemistry formulas posted on the Internet or published in a hobbyist magazine.

That said, your earlier comment about dye stability is cause for concern. That's something that's not easily evaluated by a photographer until it's too late.