The Oppo is going to be as good as or better than (probably better than) the 2910 if you use the DVI output, although as with any upconverting player you're only going to benefit if the player's scaler is better than your TV's scaler. The 2910's extra cost is largely tied up in better DAC's, so if you listen to DVD-Audio or SACD you should see at least subtle improvements by using the 2910. For regular DVD's or CD's, the analog audio section is irrelevent since you'll use digital audio output.

We did some comparisons here recently between the Oppo 971H and a Yamaha S1500. On darker scenes (Batman Begins' tumbler chase, for example), the Oppo didn't show any real benefit, but on brighter scenes (the depth charges being dropped in U-571) the differences were much more noticeable. Go for a movie with a really good transfer and bright outdoor scenes, and you'll probably have the best luck comparing the two players.