I asked about the PW4 here. I was considering getting one.
https://www.mobileread.com/forums/sh...d.php?t=325120
There was a JB released recently, but it might have been plugged already. In any case, it doesn't look good...Not sure.
If you get a Kindle off ebay, etc, you'll have to make sure it comes with old FW. It might be a crapshoot.
What do you use the JB for anyway?