Just wondering if it is possible to flash over a Eurodyne tune ECU?

A friend of mine who has someone he works with has a 1.8T 3076 Golf, and he bought into the Eurodyne hype... While I understand you 'can' make it work, the software to tune is absolutely horrid to work with.. It's slow and cumbersome and I'd rather just flash it the old school way working from a stock VW file.

Can I just flash over what is on the ECU?  If yes, can he revert to Eurodyne if he ever wanted to?  I believe it is tied into the ECU EEPROM/VIN somehow so I am assuming as long it is physically the same ECU everything should work.  But I'd like confirmation before flashing over the existing setup and turning his ECU (and Eurodyne license) into a paper weight.

Thanks