Seems like the newest T2 chip equipped rMacBook Pros won't let you use startup keys' combinations with external WIRELESS keyboards (wireless Magic Keyboard, etc.). Can you confirm this? I used to be able to press the "option" key on my Magic Keyboard when the boot chime sounds on my mid-2012 rMBP to open up Startup Manager and choose the BootCamp partition, but now on the newest rMBP I am no longer able to do this ... wonder why?