A bit more on weight limits. Never mind the air drop or how fast it flies, the bitter pill is that the good old K (even a Mk 1) could carry 2 x 4 ton trucks whereas the J can only carry 1 because of the weaker floor fore and aft. There are many variations of K load which are not now feasible.
Has anyone mentioned the vibration problems yet? On a Mk5 I believe you can only manage to sit approx 3 pax forward of TDR 10 (first two fifths of the cargo compartment) due to all the restrictions. After over two years in service the aircraft still doesn't have a winch. Why are the side para doors never opened?
All this said , interoperability should have been introduced years ago. At least NATO tried 3 decades ago to have all pongos use the same calibre weapons...