I once did a test comparing the two cameras. The sony is 1080P and the Varicam is 720P and... it was nearly impossible to see the difference (for detail). Each camera records the same amount of data. I'm not sure the custom curves in the Sony still allowed access to the full dynamic range that the camera could see though. But, if you're shooting for (getting the look in camera), then I can see how the sony might be more desirable. For post color correction, the Varicam had the edge. I will say, if you've got a Panavision version, with the Panavision lens to go with it, the Panavision lenses were quite good. And they had the advantage of not having the distance scale shift with the ambient temperature as the Canon and Fuji lenses do.
I def see a difference in detail and overall quality between the two cameras. I have the Panavision Body and viewfinder but I am using an Optex Cine HD Zoom, HJ9x5x5. The varicam is a beautiful camera and i had many fun years with it, but, once i got behind a 900 and did my tests with one, i was hooked. Like i said, to each his own. Both cameras offer great pictures in the right hands, after experiencing both, i like the 900 more.