Hello,
Nathan here, I am the lead calibration engineer at SXTH

Lots of good questions so I will try to go over them in a succinct manner.
The EK1 Pro was our first venture into the ECU flashing realm. We worked with NKLAB in Korea to create and manufacture the device and have since started a new joint company to handle all of our calibrations and device development: SXTHNK.
For the Stinger platform we currently operate by unlocking an ECU, be it a spare or original, which then allows us to flash tunes through OBD in a matter of minutes. The EK1 Pro handles all flashes through an SD card and files are stored as an encrypted format...no file sharing!
We also support reading and writing of the TCU (no unlock or spare necessary). The TCU takes about 15 minutes to read, but writing is faster. This will allow you to store multiple TCU calibrations for daily, track, etc. Super handy!
The device is locked to your
VIN to prevent you from flashing an unrelated file to another person's car and causing damage. This can be reset if you choose to sell the device.
Lastly, as some have alluded, we are currently testing and finalizing a remote unlock which does not require you to send in your ECU or purchase a spare. The unlock will be applied through OBD, after which you will be able to flash files the same way as the previous method. This will reduce cost for those who do not want to purchase a spare or have the downtime of sending in an ECU.
We work with several people right now for tuning on our platform and hope to add more in the future.