Yeah, 90% of the time this wouldn't apply to me, but I can see the utility. The same way the email clients have the "Unified Inbox" across different email clients. Most the time I want to be able to just look at one category. But sometimes I load my reader and I have like 1-2 posts in 5 different channels. For those instances it would be kind of nice to open up a reader that I knew support this "Unified Unread" and just scroll and read them. I get tired of tapping between the channels when I run into those couple of posts in each channel situations.