Yeah, this can get very expensive before it even has begun. Our specific DDE (diesels) is sealed with a special PU, similar as the one used for the windshields. The only way to read/write is to open it to connect to the processor boot pin. Openning the DDE has a lot of risks involved and i wonder how many tuners are ready to take responsibility if someone's DDE does not work anymore. R/W with cheap chineese tools also hides huge risks. I dont say anything bad about the guy advertised in the first post, just revealing some sides that most people dont think of.
I didnt even started with the short and long term effects that improper tuning may have on the engine and subsystems. Generally this engine is almost indestructible, except if someone wants to do this on purpose. But if someone wants to leave the emission related parts on the car and just get a few HP extra, improper tune may clog the DPF in just a few hundred miles. As with all things in life there are proper ways to do something and there are shortcuts.