Nigel
I guess Jimgriff could probably come up with the stats.
In terms of survivability, I agree with you the seats become "less lethal" if used within limits, and also if you are dressed properly to survive an ejection and its aftermath if we are also putting such deaths down to the incorrect use of the ejection seat. The difference between the average military and the average civi pilot, is that the military pilot will be less likely (due to aptitude, discipline and training) to operate a seat outside limits. Consider the L39 ejection at Duxford for example.
But back to the "do I bang out or not?" question. If you add a Pax to the equation, then this adds to the price of fish equation. I was speaking for myself in situations where I would have been solo, or where I was alongside another member of the syndicate - and you either decide for yourself when solo, or you look at / talk with the other shareholder, and you both agree to carry out a landing if the circumstances warrant it. if you can't communicate, and you want to stay with it, then the other syndicate member can leave by himself. Agree 100% with you that these things are better thought through on the ground rather than in the air.
The position you don't want to be in, as you see the bottom of his seat disappearing over your head, is to be thinking "I wonder what he meant by that....."