CS4 Media Encoder-MPEG 2 Quality?

Well, I've run into my first disappointment with CS4.

Actually I might be one of the few who was quite pleased with most innovations of CS4, and had almost no bad surprises.

Now however, I have run into one: the quality of MPEG-2 encodes from SD PAL material. Granted, the material is rather noisy, and on the "up-side" I have found the media encoder in CS4 to be one of the fastest ones around... BUT:
it seems the black-values and contrast are quite bad when encoding at CBR, 7,5 Mbps. I have encoded the same material with Canopus ProCoder at the same settings and the results are MUCH better... i.e. Contast/Black values are spot-on and the noise/block-iness are absent.
I have also tried using a bit of Gausian Blur in the Adobe encoder but it doesn't improve anything.

I wonder if part of the problem is the fact that the original material is an Apple Quicktime PAL-DV file, and Adobe-PC has some wrong way of interpreting this format?
Any comments/tips would be much appreciated.

regards,
Ninetto