I used to have the 200/203 combo and would be interested to hear your conclusion. It's possible that the newer DAC in the DVD players you're considering will outperform the 203 but I would expect the 200 transport's jitter and timing to be superior to the DVD player's. For what you would get if your sold the 200/203 I would hang on to it or possibly sell the DAC and get a more up-to-date converter. There was a Tag DAC for sale in the classified's section that may be worth looking at, probably based on the old Audiolab 8000 DAC which was highly regarded in it's time.
If music is a priority for you, you may want to start saving your pennies and go for something like the Audio Synthesis DAX Decade, an investment that will last you for many years. Audio Synthesis have just bought out a newer version of the DAX so used DAX Decade's should start becoming available in the classified's section of Hi-Hi world over the coming months at *fairly* reasonable prices and would be a good match for the 200. The beauty of the Decade is that it has a digital volume control so no pre-amp is required, the difference this makes has to be heard to be believed.
More details on the Decade can be found here
www.audiosynthesis.co.uk/dax.htm