The OP mentions "my D76 dev chart" which I had assumed to be the Kodak chart. If it is then there is a 2.5 mins difference which is much larger than the times differences in Tmax dev for the emulsion changes.

Maybe the OP was referring to the MDC? I don't know. However if not, then this does seem a large change and I understand his reference to "confusing"

pentaxuser