Safety and aircrew fatigue is exactly why I inquired about the HGU-56/Floatation. I flew in the Army for 15-years and wore the helmet, I actually liked the helmet. Now, my employer wants to acquire the 56 with the new Gibson Barnes ANR system. The ANR system is horrible and most guys who tested the helmet kept the ANR system off. Which leads to very poor audio quality from the passive noise cancellation. The ANR battery pack adds weight to the helmet, which increases fatigue and contributes to all the neck issues others have mentioned. Add NVG's, battery pack, and counterweight; your neck will be in pain the following morning.
Horrible product, not sure what they changed with the ANR system, but I hope my employer goes another direction. I know my Gallet may not have the best crash worthiness, but it was comfortable, had good audio, and worked well with NVG's.