Could I just cut the end off a cable and wire in my battery and use that power my FEZ (either Domino or future Gadgeteer device)?
Anything to be wary of if I were to take this approach? For example on the SP module, would this still fall under the watchful eye of the voltage regulator (assuming there is one)?
USB power is assumed to be regulated and at 5v. So you would need to handle that, but after that, plugging into the SP module’s USB port should not be an issue in my opinion.