Radar is one of the things that makes Tumblr awesome because it’s not intrusive, but it gives a window into blogs that are different from mine. I don’t plug random words into Blogger or Twitter to see who I should read or follow, but I often check out the Radar posts.
I want to see content from other users that I wouldn’t otherwise see on the Radar. So I don’t think you should allow content created by Tumblr onto the Radar.
Yes, Storyboard counts as your content. You may be shocked to find out that I already have heard of One Direction before you decided to weigh in this week, so I’m not really in the target audience for that reportage (for that and other reasons). Practically every other post on my Radar is one of yours, which makes me suspect that you aren’t shuffling that deck randomly.
I would also rather see individual users on the Radar than branded or corporate Tumblrs that are often ad-dominated dashboard hogs, but I recognize that is a losing battle.