Nostrinian - I believe you're right on the auto-eject system. Not sure how it works but it may be connected to the flight data: that is, if the nose starts to go up or down too fast, indicating an engine failure causing a thrust imbalance, you are out of there.
The problem is that almost any major engine problem in powered lift mode - which is when it's most likely to occur, given that all systems are running at sustained full blast - is apt to cause the thrust at one end to decay faster than it does at the other, so you have both sink and rapid pitch movement, at low altitude and airspeed, and that does not take long to get the seat out of its safe envelope.
Interesting about the noise. It's not, I suspect, that JSF is that much louder than a Typhoon on full burner, but that the noise on landing is sustained. Max noise on a conventional jet is transient by definition.