The ability to pull a file off the ecu via obd2 is completely disabled in code - so it only supports what's called "virtual read". Even commercial tools will read the box code from the ecu and then download the file from their own central repository.
You can flash over tuned files, depending on what key the file uses for the programming session. We obviously have the factory one and keys for some commercial tuners.
The way VW works, they have many different box codes which all use different software structures - so the maps are in different places. What we've done is consolidated around a software structure that's available on all the vehicles with Simos 18.1 (it's called s50). So golf sportwagen/alltrack, gti, a3, R, and S3 are all now running the same software.
We've got a pretty decent base file for the a3/gti (thanks
@Exley ) that I'm running on my stock hardware a3, and a conservative stage 1 file that
@J Peterman is running on his sportwagen. We've also got stage 3/MPI/Flex files (with flexfuel support for not just fuel but also ignition correction).
Tuning these cars isn't that difficult once you know where changes need to be made.
Finally, we can also recover ecus on a bench if you get hung up or there's what seems like an unrecoverable issue. We've only had to use it once and it's because
@aaronc7 was probably drunk. He purposely flashed the wrong file.
There's more details available at
www.simoswiki.com for an overview of how things work. As far as actually flashing the files goes, you can do it with a windows laptop and a tactrix openport.
Edit: Yes theres plans to do TCU as well. Brian and I both did the majority of the development and coding, and up until recently, neither of us owned a DSG car. It's on my agenda though I'm not sure how far out it is. Hptuners is the best place to go for TCU RIGHT NOW if you wanna DIY.