It doesn't matter how good you make a seat, if the pilot doesn't strap in correctly he is wasting his time.
I was brought up with ejection seats. With those it is IMPERATIVE that you push your backside right into the corner and tighten the lap straps. The same with helicopter seats; you see too many people sit in, drape the shoulder straps over them and then, as an afterthought, attach the seat straps.
My early operational life was attached to a Mk 3 Martin Baker seat which, if fired, would depart the end of an eight foot, three cartridge, tube at eighty feet/second with a 175 lbs. pilot attached. I weighed about 145 lbs. with kit so I was going out considerably faster so I welded myself to the seat. Even on extended refuelled flights of ten hours or more there was no discomfort at all.
I did the same when I transferred to helicopters; tighten the lapstraps and allow the shoulders to move with the inertial. Should you leave the lapstraps loose then inevitable movement of you backside will ease it forward and then you backbone becomes the wrong shape. That's when it gets sore and will cause long term damage.
Five years on stovies, forty three on helicopters; Not a twinge.