Just to get it out of the way - I'm a civilian and I use these devices 'recreationally'. I use them for work, but my work isn't 'work' if that makes sense. I don't run with it, I don't fight with it, and the longest I've had the whole package on my head is no more than 4-6 hours.
My neck doesn't mind weight (unless something goes wrong, but that is pretty normal). What it minds is unbalanced weight, especially wobbly unbalanced weight.
Using a ballistic helmet as a base gave me a fairly stable platform out of the gate. I had to fuck with the padding for quite a while due to the nature of the AirFrame, but in the end I got something that was fairly stable even without suspension - which was the goal.
I won't knock bump helmets - I've just never found one I liked. The outer skins seem on the thin side, they almost universally have vent holes in them, etc. The Crye Night Cap, to my knowledge, doesn't even pretend to fit. I've never tried one, but the measurements don't look remotely promising by a couple inches.
A Wilcox L4 G24 took out a ton of wobble, and a Norotos Dual Dovetail added the additional adjustment room I needed while completely eliminating any wobble that was present with the Wilcox J Arm I tried first.
At this point, everything is solid, but it was unbalanced enough to cause me some issues. I believe I only tried two counter weight systems - the EOG Gen 2, and the Low Profile Short. The EOG Gen 2, which is essentially a bag of lead shot inside a carrier, had a tendency to keep going once my head stopped. It sucked for my neck - inertia is a bitch.
I turn my head suddenly, the weight bag wants to stay put. When my head stops, the weight bag wants to keep going. Switching to the EOG Low Profile Short stopped this (well enough, I mean the effect still exists but the whole helmet now feels like one piece).
I get the concept of not having useless weight, however I do not personally believe it is applicable to my specific usage. Anything that I could use for counterweight (batteries, etc) needs to be accounted for elsewhere. I'm not suggesting that I have THE way, I'm simply explaining the lefts and rights of my situation and how that impacts my decision making.
Although, the less wobble you have (to include counter weights) the better off you are IMO.