I have been using the Decklink SDI with Premiere Pro CC and I find that it is very unpredictable.
The current project has a mix of formats and I find that when I preview 720x576 in the source monitor it switches - that is to say it takes a moment to consider the situation - and then when i go back to the main timeline I dont get anything - either black or remnant of previous SD frame. I can get it to respond by switching (Blackmagic Videohub) to another source and back again. That will usually "reset" the card to play the PP feed. It gets embarrassing when clients are in attendance.