As the article says, the copies can often misreport what code version they have, so that's of no use in determining what they can or can't do. All that can be extracted from the microcontroller is the machine code that sets up and operates the microcontroller, not the original source code, so modifying it substantially is likely beyond most of the clone manufacturers.
Further to the pirating of the original code from ELM, the microcontrollers that it runs on are also commonly cloned, and the electrical performance of the devices can deviate from the datasheet values. The most common effect is that they can occasionally lock up, and will only reset by being powered off for a few seconds by unplugging them. PICs have a built-in "watchdog" that monitors for this, and resets itself automatically, but this may not be implemented on the clone hardware - or even on the early version of the genuine ELM for all I know.
Practically, there's little difference between any of the clones, they all run pretty much the same code, and my $7 device has worked in every vehicle, and with every OBD scan app or virtual dashboard app I've tried.