I have both clone Tech2 and MDI interface from China. Here, I’ll chip in with my experience and give you some tips if you have a GM and consider buying a tool for it.
Cloned GM MDI interface:
MDI/GDS2 is used on C7 Vettes, and other vehicles prior to 2014 (for example, Chev Cruze starting in 2011 uses MDI, as well as others).
Cloned Tech 2 Scan Tool:
I use the Tech2 on my 427 vert as well, and it does everything stand-alone except module recalibration (programming or ‘flashing’).
Btw, There wasn’t a single all-inclusive model year where they cut over from the Tech2 to MDI for all GM models. It had more to do with platforms that were more-or-less fresh designs or clean-sheet designs after about 2008 or so.
Why MDI interface is more preferable for GM:
Flash faster: MDI & GDS2
As for why GM is going to the GM MDI and GDS2, instead of using a Tech II with TIS2000 software, because the MDI with GDS2 flashes a hell of lot faster when you have flash a new module with either it orginal firmware or upgraded firmware. Its also faster to use than having to press buttons on the Tech II for basic commands during diagnostics as well.
Older cars: Tech II & TIS2000
So in regards to the vets, Tech II clone will cover all the C6 cars and older since the last of the updated firmware on the unit covers from here back. If you do need to reflash something, it’s done via Tis2000 with the Tech II as the pass through device.
New & old cars: MDI interface
Since GM did not make upgraded firmware to flash into the Tech II’s to cover these cars like C7, then it’s a MDI that is needed instead. As for the MDI’s firmware, they will cover not only the new cars, but the cars that the old Tech II’s used to cover as well.
Now the glitch on the MDI regarding cloning it, since it has to use the GDS2 software for the pass through only device, GDS2 software has not been cracked like Tis2000 software has been instead.
GM account for subscription: MDI need it
So the only way that even a clone MDI is going to work, is to have a subscription to GM (Few $K a year) to allow you to use the GDS2 software that has to log into GM each time it used instead.
Hence the Clone Tech II unit you get will already be loaded with the most current firmware, and for most of the stuff you going to use the Tech II clone, will just be using the unit by itself without being connected to a laptop
Also the cracked copy of TIS2000 that you get with the clone model, does not have to be connected/logged into GM to use it for 99% of the stuff (do not need an account with GM).
Note, if push comes to shove and you can not find a copy of the needed firmware to flash into a unit to upgrade a module, then you can get a one day subscription to GM to pull down the needed file from them.
Another place the people have had good luck with as well.