Perhaps it's interesting that around the time Multi-coating became common the contrast of colour films changed as well with newer emulsions and processes like C41 and E6, also K25/64.

I think exposure needs to be taken out of the equation Dan, it's long been used for controlling colour saturation particularly with Kodachromes regardless of lenses being coated r not. Also I've found newer Copal shutters often run slower than Compurs of any age (that aren't sticky). I have tested my Compurs and some Copals and even a 1913 compur is still remarkably accurate.