My tuppence worth as military aircrew of 11 yrs experience and a survival instructor of 7 yrs experience...
Having deployed to Iraq in 50 degrees I always wore full thermal underwear and fire retardant clothing and gloves, no exceptions. Dehydration can be managed, being trapped in a burning aircraft can't without Nomex. I have 3 friends who have all had horrific burns and lost parts of their bodies as result. You will never regret wearing it.
I cannot fathom why anyone would want to risk it when it can be mitigated against so easily and cheaply. Civilian leisure flying carries the same risk of fire and I suppose a greater chance of crashing due (generally) to less hours and experience. Military crashes tend to be more catastrophic and to be honest a Nomex suit wont help when you fly into a hillside at 420 kts!
Do yourself a favour, wear 2 layers. The under layer made of cotton and the outer layer nomex. eBay is your friend, rather than spending money on flying hour, buy some Nomex clothing.
I am not for a minute saying this is the only answer and others are wrong, it is merely my opinion. You are all adults capable of making your own decisions
