mmcp42:
the limits they mention apply if you're using the on-board regulator(s)
you can just feed 5 volts regulated directly into VinWrong, Vin just feeds to the INPUT of the on-board 5vdc regulator. You can of course feed a regulated +5vdc to the shield +5vdc pin.
looks like I may be going the higher voltage route after all
I want to keep running at 16 MHz, hadn't spotted that part!