Since you must balance 9 emulsions (on average) for color, it is more critical to have one process for all. Agfa failed years ago with their own proprietary process when Fuji and Kodak were using the same processes.
B&W is quite different and allows a larger variety of emulsions to be used. Of course this becomes critical with 3 emulsions in some cases in one B&W product.
I remember reading some Jobo literature on the web that suggests not processing Kodak and Fuji together. Sure pro labs do it but they have huge tanks with probably a gallon of chemistry per tank. You are putting 300ml of chemistry in your Jobo or so- much different.
Color is easy in this regard: E-6 is E-6 is E-6. C-41 is C-41 is C-41. It is black and white that is the problem when it comes to mixing films in the same processing batch! Color films are designed to work in a standardized process. Black and white films are not.
Of course when you start messing with non standard processes such as cross-processing E6 in C41 or vice versa, all bets are off
"Flatter Me, and I May Not Believe You. Criticize Me, and I May Not like You. Ignore Me, and I May Not Forgive You. Encourage Me, and I Will Not Forget You."
Sometimes I wish colour had a non-standardised process, as I fantasise about this having given more freedom to film R&D on colour films - higher speeds, flexibility of Tri-X and others, oh well.
guess we have completely different mindsets. I'd rather do all my creative workings with the camera and film and not worry about variations in developering and agitation. The only time I want to change or adjust developing is when I cross process or push process, which is probably 1 or 2 rolls a year at most
I understand the creative possibilities, but sometimes I think too many possibilities can be detrimental, IMO. I make a print that I think looks good, then I think, "well, if I had done this or that, my picture would have looked "better." I put better in quotations because in reality, my prints would have looked different. Not better or worse, just different. I probably convinced myself that less variables would be better just because I tend to think of all the stuff I could or should have done
Edit: I hope this post doesnt hijack the thread.
"I have captured the light and arrested its flight! The sun itself shall draw my pictures!"