I wear a nomex flying suit and nomex gloves when fllying the Pitts, but not when flying the Taylorcraft. Why? For a couple of reasons. One has to do with loose articles in the cockpit and no storage in the Pitts. A flying suit has plenty of pockets for everything I need during a flight, and it keeps them all secure. There's also no heater in the Pitts so a flying suit keeps me a little warmer.
But with the flame protection issue, I look at the energy involved. The Pitts comes across the fence at about 90 mph and the fuel tank sits right over your knees. At that speed, I'm more likely to cockup a landing or have an accident with higher energy and possibility of breaking things up. The Taylorcraft comes across the hedge at about 55 mph and finally touches down at around 40 mph. Add any kind of a headwind and you can see it reaches the ground with considerably less energy and is much more forgiving. So I reckon the chances of getting into any real trouble is much more limited. For the same reasons I wear a helmet in the Pitts, not in the Taylorcraft.
As an aside, nomex is inherently flameproof - it's intrinsic in the fabric itself and isn't the result of a treatment of any kind; meaning there's nothing you can do to it (including washing it every day for 10 years) which will make it any less flameproof than the day it was made.
Pitts2112