The flight suit topic has come up from time-to-time as has the helmet issue. For me, I started flying with a flight suite for a very simple reason having nothing at all to do with safety. Sunburn.
I fly back and forth from CRQ to Phoenix almost every weekend and when weather permits (which is most of the time) I would take my 44 (and now my 500). I would wear what was comfortable - shorts and a short sleeve shirt. After a couple of times doing this I realized that I was getting sunburned on the tops of my legs and arms thanks to the wonderful forward view I had in my 44.
I choose the flight suit because I can easily slip it on before I jump in the cockpit, I did not find it uncomfortable or too hot and I never got sunburned again flying in 110 degree weather over the desert.
A secondary issue was about safety, but like many of you, I have seen the pros and cons debate on headsets and flight suits since I joined VR and didn't see a clear winner either way.
Having been in the Marines, I do know that all military flight crews wear flight suits, I know that every police department that I have ever seen flying wears flights suits, I know that every EMS operator that I have seen personally flying wears flight suits, I know that every firefighter flight operation I have seen wears flight suits. That's a lot of professional pilots wearing flight suits.
In the end, all I REALLY know is I don't get sunburned any more and that is good by me!