Also if a pilot makes a 90 degree turn, in the situation they're under will they select direction of turn toward the more suitable aerodromes for landing should they need to get on the ground ASAP? I doubt they would have time to even consider this.
I know that UK Area and Terminal centres retain the datablock with callsign and have a box flashing around them should you select 7700. Depending on which emergency Sq you select (7500/7600/7700) our third line of the box is filled with either HIJK/RTF/SOS so we know which ones selected. At Swanwick the box around the callsign flashes red and yellow. I don't know about other European centres wether the callsign is retained, but I'd imagine that there are a great number that do.
Personally, I'd want you to continue in a straight line and get 7700 going ASAP.