First, I think it would be a great idea for any future Single Board Computer or Router designer -- to design their product such that it will work with any power supply from 5V to 12V (assuming that the power supply can provide enough amperes at that voltage).
Even better might be to design a SBC or Router such that it works with say, a minimum 500 milliamps at 5V -- which should make it compatible with just about any consumer power supply out there...
Yes, I know this is wishful thinking for several reasons. But let's look at the WRT54G & WRT54GS -- apparently these will work a power supply providing any voltage from 5V to 15V -- so long as it provides enough amperage at that voltage...
To be able to accomplish this is a great design practice for Routers, SBC's, and other small computing devices.
Also interesting: Look at the table of input voltages, supply current and watts.
Note that Watts, in general, goes down (not by a lot, and not at every voltage, but generally, linearly) as Voltage goes up...
That's an interesting effect...
If the article is correct, then this seems to be the work of the "integrated 150kHz step-down switching regulator".
I think it would be highly interesting (at least, if you are a SBC and/or Router manufacturer) to test all available step-down switching regulators -- and craft similar tables of input volts, amps and watts -- over the regulators' range of voltages. (Octopart anyone? https://octopart.com/)
Which regulator produces the best response over the range of voltages it handles, and then, go an extra step -- research and discover WHY that is, what are the reasons in Physics -- for the phenomenon?
I think that that would be a highly interesting endeavor!
(And of course, I'm also open to any suggestions for webpages for people who have already done this, or something like this!)