The problem with going back to chip change, something that usually used to be done because the flash memory was write-once (so you needed to read the old chip, flash to a blank chip and re-install onto the ECU board) is quite a lot of modern ECU's do not have a flash memory chip anymore in the traditional sense. A lot of the more modern ECU's such as the EDC17 ECU's with the Infineon tricore processor have the map data stored directly in memory built into the processor. These are the same ECU's that have since started shipping with TPROT software (Tricore Protection or Tuner Protection, depending on who you ask!). As a result these ECU's still need to be removed from the vehicle to be flashed - as flashing via the OBD port without the correct RSA key will result in TPROT being activated (car won't start - its like the IMMO being on). TRPOT can be removed however in boot loader mode, so its a case of TPROT delete on the bench, and then the car can be flashed via OBD.