MacBook Air here, with Bootcamp running Win10 on an USB drive running AH3 without a hitch.Best <S>
One word of warning, this was back a few years running bootcamp on the big imacs so this might have changed: Apple never provided power management drivers for Windows - so bootcamping Windows usually involves the Mac running at full tit - i.e. hot. So keep an eye on the heat side of things.