I contacted JOBO tech for information on a "Protectan" subtitiute - got a "You're on the List" answer ... so I'm waiting.
While I was there, I mused about and came up with this information from their "Support" section ... "JOBO Quarterly - Issue #4 - JQ9404." This was written by Paul Rowe, a much missed member of the JOBO organiztion who passed away a few months ago.
The article was titled: "Color Negatives - The C41 Process".
Paul had conducted quite a bit of research into the process, with specific consideration to uniformity and consistency of processing - these were his conclusions:
1) Pre-wet of the film produces unpredictable variations.
2) Acid stop bath introduces unpredictable variations.
3) Rinse (using water instead of stop bath) after the developer introduces unpredictable variations.
All of which seems to agree with my own experience, although I haven't been anywhere near as thorough as Mr. Rowe was.
The *ONLY* place I use stop bath now is in RA-4 Color Printing... I believe it *IS* necessary there.
I know it is risky to try to extrapolate this to Black and White processing - but I think there may very well be valid parallels there.