Just now, Darth Meanie said:...
Imperial defectors would qualify. Agent Kallus and Mara Jade come to mind.
...
Well not really because defectors are most likely one way because once someone turns on you you really don't care to see them back. a Rebel or Imperial only as far as characters go would be more of a double agent or something that both sides have decide to keep because thy prove useful for the moment and the near future but will likely terminate after they are finished. For technology I could see as some sort of restricted military tech maybe used by the Republic in the clone wars that wasn't available to civilians. But then again explaining how scum can't get a hold of it since they can nearly get their hands on everything from glitterstim to a cloaking device it can prove to be difficult.