They uses choppers very bad. Light attack helicopter like the Pawnee mostly don't hit anything. You can't use them to attack Infatry, vehicles or anything else. As zeus i placed a CSAT squad. Then i placed a Pawnee and gave him the order to attack the soldiers. A few seconds later he was destroyed without making a single kill. I placed another chopper who got shot down too. I procceded this. After the squad shot down 4 choppers they nearly stopped shooting at the fifth one (They still had tons of ammo no idear why they stopped attacking). Finally the fifth chopper was able to make some kills. But after 20min still some of the CSAT squad were alive.
But the behaviour of heavy attack choppers is not much bether. Mostly they only use their guided missiles on a distance more then 3000m. I spawned 5 Kajman 1000m arround a mora. The mora destroyed all of them without problems. The heavy attack choppers attack very inefectiv and are nearly useless in most cases.