Catchy name.
The usual dividing line for system differences is PW | PW2 rather than PW2 | PW3 (Different SoC with different cpu devices).
Which only means that it might work on the PW2 and might not work on the PW.
That is, one device model older than expected.
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When hot-plug support work is being done, you will probably be able to handle (or at least avoid) those combinations that leave the Kindle's system in strange and unusual states.
Even with a stock Kindle, plugging in a USB cord from a PC generates a lot of internal, low level, activity to get the result people are used to.
All of that work certainly wasn't done in a day (or a week) by lab126, and it might even be why they haven't (at least yet) included general USB device support (although the hardware (since the KT) can do it).
- - and they probably have documentation to help them - -