Can you use the SERT data mode without having the copy of the SERT MAP
loaded on the computer? The dealer said he can't make me a copy for about a month he's waiting on new computer. Could just be B.S.
Yes, you can use the data mode no matter what map is loaded. Data mode just gives you feedback from all the sensors on the engine.
I think the dealer is feeding you a line of bull about not being able to give you a copy of your map. I've got a suspicion that a lot of "custom" maps are nothing more than canned maps or slighty altered canned maps that are sold for big money.