What purpose do you see the replacement having.
If you are looking for something to cut harnesses (to stop crew burning to death and making nasty screamy noises) then forget the knife.
It is large, cumbersome and has a pointed tip which is REALLY stupid.
Crew may need to use an escape tool when they have just crashed (so a little un nerved), it may be very dark or under water, they may be using their non writing hand and will be working in a confined space and very close to their pink fleshy parts.
Is that really the place for a double edged pointed weapon?
The J cutter is slim and will naturally slide into position and will automatically find its target. It takes less mechanical movement to cut a harness and won't cut anything else.
If however you are looking for the knife to perform other functions then consider this:
The crew may have side arms for personal protection.
People tend to shy away from sticking pointy metal objects into other humans even if they are carrying a blade.
There are other places to store weapons and equipment for use after a crash that are not directly strapped to crew and so cannot injure them during a crash.
There is also another option that many people overlook for various reasons.
If you were to look at people who cut harnesses and seat belts on a regular basis they would use first aid shears. Shears will easily cut through a harness and will also cut through thin metal (they will cut through a coin such as a two pence piece). The shears are way more effective and safer than a bladed knife, but are not as easy to use as the J cutter.
Last of all there is a reason why air crews were really glad to ditch knives (both straight and curved bladed) in favour of J cutters
