My twopenneth on aircrew knives:
Latest Mk1 is by far the best for what it is designed for: cutting seat straps, parachute straps and rigging lines. However, as a knife in survival it is plain sh!te.
Older curved types were as already stated: clunky, normally blunt when you wanted to use it and also sod all use in a survival situation. I was once stopped at Cardiff Airport by Security having diverted into there in a live Q jet - I had to give up the curved knife to go and make a phone call, even after protesting that the Queen trusted me to fly 8 missiles and 170 rounds of ball and tracer around the UK, would it not be ok to carry a pants knife??? I ended up surrendering the knife!
As to suggestions: I would suggest a j-knife in the same way as the current Mk1 cutter but with a longer, retractable and lockable blade for survival purposes (and stabbing the stole of your LSJ if you need to).
LJ