It does work... that is... on some macs. The issue with apple is they really don't have any idea about how to design a computer.
Yeah, whatever you say... Now I'm supposed to take anything else you say seriously?
A few things to consider: if you've got those wireless keyboards that run on bluetooth - yah you aren't going to be able to actually get the mac to know you're holding that boot menu key down until it's too late. if you're plugging your flash drive into a USB port that isn't directly on the mac (like on a keyboard or hub) then yah, that isn't going to work either because mac isn't able to discover deeper than one device before it's booted.
No wireless keyboard on bluetooth. USB stick plugged directly into the side of the laptop.
If you're on a macbook - you're going to need the have the mac plugged into an external power source before any bootkey will work, if it's not on power the mac waits to turn the keyboard on until you're at the desktop.
Plugged into the external power adapter continually throughout hours of failure attempting a procedure that
obviously does not work and I'm not the only one who's been SOL trying by far apparently.
Those are about the only things I can think of that might affect your ability to boot to a usb stick.
Well thanks for playing then...