The difference in cross-colour artefacts (rainbows) in the subs in very clear, the Theater card is much better in this respect.
The fact that you get dropouts with the PCI card is surprising, as I always thought these were down to the disc or player. Never heard of the capture device being responsible, but there you go. Possibly a faulty card?
Do you have any discs that contain test patterns? A capture of such a pattern would be a more useful source to compare performance.