I believe the SD contents is console dependant, however whats written to the USB drive doesn't matter (the MAC address is only needed for the initial payload aka LetterBomb).
My goodness! This is an accident waiting to happen, reminds me of that one EEVblog video about the awfully made tablet sold for hospital use. Absolute disgrace.
Hey hey! Been into hardware modding and electronics for several years, hoping to learn some things and also give back to this place in the form of a neat project or two. <3