RMC,thank you~
i agree with your "Yes there are a lot of clear rights and wrongs....obvious gos or no gos...but there is also a lot of grey in the "unsafe to fly" catch all."
this phrase "unsafe to fly" is quite"grey"
it`s situational~
a proper rejected take off decision is quite difficult, because it`s unexpected, sometime complicated and the time for you to think is really tight!
i think we`d better check the QRH for the max speed for aborted take off with the brake energe acceptable before every flight. to difine another speed sector for the GO and NO GO~