We have a HPX500 so we can only capture P2. I recently had the opportunity to view down-converted DVCPRO HD thru a Decklink card and then a Kona card in my system (Mac Pro early 2008 dual quad 2.88) on a Sony broadcast monitor, and the Decklink was noticeably softer than the Kona. Startling, actually. I am monitoring analog component, not SDI. Hope this helps.
Peter Tours
TnT Video Services, Inc.
Fort Lauderdale, FL