How do you use them?
What's the point of HAs in combat? The extra armor is nice, but with that many Oni running around, heavies just can't do anything. I've played games where half the team got HAs, and a few oni turned the tables too fast to even respond.
For every onos there is, that's a nullified HA. And when HAs become popular, all the former blinkers decide to go onos, making the HAs even more worthless.
Marines win all the time with GLs and JPs, but once you even try HAs, you might as well give up. HAs are only for fun-- something to try if you don't care about winning. I've seen heavy trains done pretty well in CO, but they fail in the end.
I love NS. I've played it since the time fades got acid rocket with the 2nd hive, and jetpacks were the equivalent of flying. CO just boils my blood.
BTW, is there any way to get a Gorge plush?