My experience is about the same as Shytorque's. The training rig was pretty tame; they used a reduced charge. But it was OK for getting drills and posture sorted.
The near ejection was in a Meatbox at night between Juba and Khartoum in 1955. The ITF was giving me a hard time, I had lost both VHFs, the oxygen tank was leaking and I was running out of fuel. Also the pressurisation/cockpit heating had packed up, and I was shivering beyong belief. I decided (if that describes what passed for a mental process) to carry on to DR posn overhead Khartoum and then do max rate descent. Broke cloud at about 30 grand and there, miraculously, was the sheen of both branches of the Nile and the dim lights of the town.
The prospect of banging out evoked visions of bloody great crocs with their beaks open!
Physiological effects? A marked loosening of the bowels and a desire to urinate; rythmic contractions of the anal sphincter (the "sixpence/half-crown" phenomenon).
I shouldn't have been there. GASOs prohibited night transit flights by single-seat jets and required all such flights to done in pairs, because of the lack of navaids and the unreliability of the VHFs. But I had been delayed and had to be back at Abu Sueir the next day on pain of death. And I was an A2 with 1,000 hrs on type and was immortal. I was too ashamed to write it up for Wg Cdr Spry.