Nope, as usual in Kindle 5.x land: when we mention a specific FW version or a specific FW version range:
we mean it!
If you happen to get a PW4 with a different S/N, give me a shout. I'll at least expect a 3G (or would that be 4G now?) variant to show up fairly soonish

.
Stuff from my snapshots thread *should* be PW4-ready, the only real question mark left is to see if USBNet is as finicky as it was on the KOA2. The hardware is a bit different, so, who knows

. (For reference, that involved a kernel crash when switching *back* to USBMS).
The very latest KOReader nightly *should* also be PW4-ready (but if someone tries, I'd like to hear about it, in particular to check if the frontlight behaves properly).