A lot of folks use PVS-14s just fine without any counterweights at all, and the majority of the time that I spent using them was without a counterweight, and I didn't really find it to be that big of a problem, though I do now prefer to have some counterweight.
IMHO, counterweights tend to become more important when you start getting into heavier dual setups.
Some of this was discussed a while back in another counterweight discussion, and I actually ended up making a chart of "recommended" counterweight weights and configurations with some rough figures:
http://www.ar15.com/forums/t_6_18/433794__ARCHIVED_THREAD____Helmet_counterweights_thoughts_.html&page=1#i4161106
::shrug::
While I'm a big fan of counterweights now, I've never really liked the idea of "dead weight" as a counterweight. My earliest counterweights were loaded pistol magazines, but it became more of an issue in terms of training environments, as it's not always prudent/possible/allowed to be wandering around with live, personally purchased ammunition hanging out on the back of your head.
An MS2000 strobe is an almost constant for me on the helmet, often combined with things like spare batteries, multi-tools, etc. that I would be carrying on my person anyways, to get some utility out of the weight.
~Augee