Former Session Buddy user. I'm using Session Sync and it's pretty neat. I think Session Buddy UI is still better and Session Sync needs some improvements (such as selecting multiple tabs in a session simultaneously). However, once I got used to it, I didn't miss it at all.

In addition, I like the integration with Firefox Bookmarks. It creates a folder "Session Sync" and stores sessions as sub-folders. So, if anything happens, I still have them as simple, curated bookmarks.