Your comparing generation 7 devices vs. generation 8 devices.
Amazon/Lab126 as a general rule does not backport firmware developments.
Although we probably could.
You willing to possibly sacrifice that bare PW-3 board?
Try installing a generation 8 u-boot build on it.
If you can't figure out how to do that, PM me.
We can search the forum threads together for the bit and pieces of information necessary.
OR
It should be possible to run u-boot under qemu emulation if all you want is a listing of its built-in commands.
Your favorite web search tool should be able to find you directions for doing that.
This is the set of instructions I was going to try first (when, if ever, I get the time):
http://www.elinux.org/Virtual_Development_Board
Oh...
You'll need access to a Linux based system for most of these things recently discussed.
A decent VM of a full Linux distribution should be enough, you shouldn't have to make your Windows machine dual boot.