Appreciate the dealer perhaps looked at the car at short notice, but given the fault occurs at 70-90mph then its a bit pointless doing a run round the block at 40mph. The ecu may have logged something but might have been better to have gone when you could have had the second option of putting it on the RR.
Problem with REVO is you can never put it back to VW mapping, only REVOs version - not sure what this is, the first original Mk6 GTI map they uploaded, which could now be several versions old if VW are constantly tweaking ?? The fact that REVO sort of acknowledge they've seen it elsewhere would make me suspicious, unless they could say x component isn't up to the job. The revised map should work on a standard car and not rely on having to further update other components to make it compatible.
Bluefin would have allowed THE standard map to be put back, albeit with the flash count change , so you'd have a chance of a warranty claim if any VW component wasn't 100%. However under the normal map the fault may never ever appear.