I just read the announcement about the new cabin editor. I am however not sure if I understand everything correctly...
Our largest legacy seat is merely half the size of our largest new first class seat
I am sorry but you lost me here... I never heard of a legacy seat :-)
Giving the old seats ratings that correspond to their new counterparts will be unfair because you can fit a lot more of them into your aircraft.
The current standard/economy/ecoplus seat is bigger than its new version, so you can fit more of them (new seats) into the aircraft.
The current standard/economy/ecoplus seat is smaller than its new version, so you can fit more of them (old seats) into the aircraft.
Simply using the new scale will give economy class seats a rating that's too high and business/first seats one that's too low.
Does this mean the new economy seats are smaller, so the old rating would be too high after we have installed new seats ? And the new business seats are bigger, so using the old rating would give our new business seats a rating that is too low ?