> OTOH, spoke with an old GulfAir Captain long ago who stated emphatically that he would never take an aeroplane with an engine fire into the air, no matter what the speed. <
That's the main reason for automatically disabling the engine fire annunciator on takeoff above certain speeds. Far better to fly the aircraft first and then deal with an engine fire.
In-flight engine fires are rarely catastrophic in the air once the fuel has been shut-off. Most of the bad experience has been pool fires under the wing after the plane has come to a stop.