I hope you will pardon me for jumping into a discussion I have no expertise whatsoever to contribute, but having read the thread I think the original question:
Would be interested in PPRuNe views on the safety improvement that would be achieved
has been largely answered here:
I suspect that the advantage of a rear facer is limited to reduced headstrike, and perhaps flailing, injuries
To summarise the rest of the answers: limited safety improvement, other risks introduced which have not been thoroughly investigated, additional direct and indirect costs associated.
I hope I got the above right?
I have heard people say in the past that rear-facing is safer, but I have never seen the body of research (which probably exists) confirming and quantifying that assertion.