Last time i heard from @
nelsmar he has done about 1500 flashes, i know several people who have done 300 or more.
OFT will still talk to your ecu if dealer reflashes a new rom to your car. But if you havenot flashed to stock before service then you wont be able to marry up to this new rom. However you will still be able to flash your tined rom over the new dealer flashed rom.
OFT looks at two things your original stock rom calid that its married to and will only flash rom with same calid as your stock one and the VIN number of your car.
The only time you will run into trouble is if the dealer replaces ecu say due to cam issues and the technician at the dealer either dont type the vin into the ecu correctly or they forget to enter the vin. Then oft will refuse to write as vin has changed
Their are no TSB to flash ecu after about late 2013 and any usa car with B01C\D calibration will not need a reflash by dealer at the present time.