[Goz3rr]

> Note that Watts, in general, goes down (not by a lot, and not at every voltage, but generally, linearly) as Voltage goes up...

I would say it flattens out pretty quickly and doesn't keep going linearly. This probably has to do with the fact that the device was designed to be powered from 12V so the supporting components of the power supply would have been chosen to maximize efficiency around that input voltage.

EDIT: I was curious and had a WRT54G v2.2 laying around (unlike the 1.0 used by OP), which results in this graph: https://i.imgur.com/CBNTtRI.png The lower power usage can probably be explained by my later revision having less LEDs and more integrated chips instead of several discrete ones.