Hey Flipout,
You said that they were marked with reflective tape? is it sticky tape on one side. if so It may be worth collecting some and bringing it to the police station(if you filed a report) There is a good chance that they have left finger prints on the sticky portion of the tape. If it was punk kids in the aera there may be a chance that the kids may have a record and prints on file at the local police station. It may be worth a bit of your time to investigate.
Sorry to hear though. Did you read my post on preventing stand theft thread. time to get a dremal tool and some blades. I' d bet you can stop future thefts with the method I' d mentioned.