Audphile1,
I've used my mod'd Oppo 971H as a transport and it is about the equal of the dedicated CD players and transports I've used. However, it is highly modified, so I can't compare it to a stock unit. BTW, the mod is so good that I didn't notice any improvement by adding an external NOS DAC.
In the past I've tried using a Sony S7700ES, S9000ES and NS999ES as transports and none of them equaled the performance of the dedicated CDP (used as transport) that I had in the house at the time.
If you really want a transport and DAC, I would highly recommend picking up a dedicated transport or high-ish quality CDP instead of a DVD player. In my experience, they sound better and are much less hassle in that they don't require any configuration, video screen, etc., and they typically load the CD much quicker.
However, if you really need to cut down on the total devices in your system, I understand the desire to combine CD and DVD playback into one device. But if the goal is to cut down on audio shelf real estate, maybe a quality mod'd player would give you enough performance for all types of shiny disc and you could replace both the transport and DAC with one box that has even more total functionality.
Enjoy,
TIC