Transport helis have needed the HP nerf for a long while. I pilot helis a lot and I still knew that 4+ direct hits with an M5 to kill a transport was beyond stupid.
It's the other helis that don't need any more nerfs. Nightbird's offensive capabilities have already been nerfed 2-3 times now, yet noobs still complain.
The attack helis (apache/hokum) need small buffs. They weigh like tanks and need more speed in gaining altitude. 127mm AV pods do AWFUL damage per hit on armor despite being what they're designed for, and it's hard enough to land direct hits with these things when the GUI remains inaccurate.
Gunner seat on stealth helis needs a buff or new weapon because spawning as gunner in them is pointless.