And Mmo testing.
It's not clear to me that anything less than ejector seats would be an reliable means of escape, particularly if the pilots/engineers were experiencing +/- a couple of g.
I have seen 'Bus test pilots claim that the orange suits and parachutes were mostly a box-ticking exercise.
With a hatch forward of the engines there is a risk of the test pilot causing foreign object damage to the engines! Or would you wait for them to spool down
