For what it is worth, my Denon AVR-3300 has very intermittent locking to the 811. Shows that are DD will lock on the Denon, but the Denon display sometimes says it is in ProLogic mode, sometimes DD. I always get a lock though.
At the moment I am watching HD Sopranos on HBO channel 9456, and I am getting a DD lock on the Denon

Interestingly, the first part of the show, which is a review of the past weeks episode, locked ProLogic on the Denon, then when the "new" part of the show started, switched over to DD. It was obvious that the sound had changed, and I noticed the Denon display had changed. Anyone getting the first part of the show in DD?
Does your Denon work with any of the remote codes on the 811 remote? Mine doesn't.
Keith.