How far back is Apple signing?

I had ATV on 5.0.2 but never backed up. Now im on 5.2 I miss my PLEX client. Is there anyway to go back?

For any release earlier than 5.3 you need to have shsh blobs for that release before you can go to it.


So only if I backed up? I think I backed up on the ATV flash option while playing with my ATV one time. I was really green at Jailbreking and still learning. How can I tell what SHSH bloobs I have backed on the ATV? Tinyumbrella the only way?