I have the 45-90mm zoom and all the 645 lens available and at the focus range beyond 1.5m to infinity, on my previous P25 and now P45 for 6 months, absolutely perfect! I can hardly critic its sharpness against my other favorite 120mm Apo Macro, on both pack shot or fashion/protrait works. The sharpness is good all the way done to f/22, less on f/32, which is 1 stop short, while the 120mm macro sharp only until f/22 on P45, becoming soft from f/32-f/45, the the effective shrpness is 2 stops short.
I have read many critics about the lesn not able to resolve what the sensor could offer, I did see visble improvement from P25 to P45, and the quality jump must also contributed by the lens capability.
Back in the film date I never developed much love wiht the 210/4, but now also use it more often because the lens seemed work better on digital capture. I think with P45, I become more pleased with the Contax 645 lenses.
It is interesting that you mention the 210/4 as being better on digital capture. I noticed also that the 210 seemed better on the P45 than it ever did on film but thought it an anomaly. Could it be that the 'un-filmlike' quality of the digital file makes image contrast less noticeable?