Would it be possible to add filters to the Edition pages? That is, while looking at all cards in Set A, filter to show just a subset so I could easily tell which cards in that subset I don't have?
For example: I want to make sure I have all white cards in Champions of Kamigawa. I go to the Champions of Kamigawa Edition page while logged in and add a filter to show only white cards. After applying the filter, I see the same view (with rows for both cards I have and cards I don't) but all nonwhite cards are not displayed. From there, I can just scan for 0s and easily identify which cards I still need.