Jim,
Having done USAF and USN flights as well as my RAF experience I would say its horses for courses. There will always be a compromise between comfort, mobility and utility when viewed against protection and function. Some examples: the USAF/USN flying helemets and masks are much less cumbersome than the equivalent UK counterpart, BUT the level of protection afforded by the UK helemet (in accordance with the specification) is greater, both in terms on impact and blast loads ie the UK is qualified to more rigorous standards. Duty of care appears to have a higher weighting in UK considerations than in other areas.
Your average UK ADV pilot wouldn't bat an eyelid over 2 or 3 layers of thermal protection under and immersion suit under the g-suit and LSJ. But you try taking a pilot from the southern parts of europe and puting him in the same kit then that's a different story. The North Sea being a somewhat more hostile environment than the Spanish plain (with or without the rain!).
What is impressive from my experience it the level of protection afforded by the Typhoon kit, whilst still providing IMHO acceptable comfort and mobility. Equally the helmet has managed to incorporate all the electronic gubbins while maintaining or exceeding the current blast and impact requirements while increasing the mass by only about 100g over the current in service bone domes.
However, pilots being human (contrary to popular belief) like what they are familiar with, and don't like change - I've got my lucky flying gloves and no matter how many holes they have or how much oil is ingrained into them I don't want to change them!
Watching the US aviators strapping into the JSF cockpit rig with a Brit harness (as opposed to the US standard torso harness) is a joy to behold. Both do the same job, but in a different manner, you'd swear it was cryptonite to Superman.
Time to get back on my head.
T