A question for the Typhoon drivers
100 series Hawks have a HUD repeater which is depressed below bore sight. As a result it can be a bit tricky to get used to. This is because there isn't room for a second HUD.
Speaking as someone who spends a fair amount of time in the back of a 100 series Hawk I can safely say that I'd take a HUD looking at the back of someone's seat any day. I can't imagine it causes too many problems unless you're trying to demo a tracking guns shot or do a flapless landing (I have never flown a Typhoon and I stand to be corrected). Since dumb bombing has had its day these are about the only times it's likely to be an issue.
I am not disparaging the Hawk by the way. It is an excellent training platform but it does have its challenges.
BV