I agree with blackhawk about comfort/serviceability; helicopters also suffer from vibration just like us, it breaks them in the end. So to improve the cushion is an okay move; however it still doesn't doesn't fix the basic geometry of the seat which in the case of the 76 is unfixable due to lack of space fore and aft.
If you use a lumbar support you'll introduce a curve into your lower spine at the point where it's bearing the load of the vertical bouncing forces; the spine is designed to absorb moderate vertical loads. It does less well when it's curved and you end up wearing the inner surfaces of the joint and reducing the clearance between L!,2, 3 and 4; in short it gets progressively more painful as you get older.
After we got modified Puma seats on the 61 with adjustable leg supports and armrests I stopped using a backrest. By using the armrests I rested my back from vertical bounce in the cruise and by sitting with my bum hard up against the seatback I ensured my back was as near vertical as possible. Backache was reduced to manageable thereafter. BUT you must take care of the back by exercising to keep it flexible; can you put your fingers flat on the floor without bending your knees? Try it, but remember in this industry to keep your back to the wall...
One other point; project engineers/pilots are very knowledgeable people to whom I defer on all technical matters. But only the pilot and the line engineer/mechanic know what it's like to live with an aircraft type for years and years and thousands and thousands of hours without relief or respite. That's what gives us a different perspective on NVH - noise, vibration and harshness. You can make the aircraft stronger to protect it but not the human body.