Collective feedback is, in my opinion, a bit broken, when lowering collective the helicopter is responding to the pitch controls in insane manner, almost as if it would be risen collective but with downward force which causes the helicopter to slide like crazy.
The angles of machine guns in Blackhawk are ridiculously small.
TOW missle, in my opinion, should incapacitate helicopter rather than destroy it, as well as cannon fire should be forcing the helicopter to land more often than just popping it out from the sky. To tackle this I would say helicopters need bigger zone of being "on fire" so that the pilot can land and fix it if he is skilled, that way with the implementation of damage to engine and rotors it would make it more interesting to use the helicopter and that way the respawn time could be made longer (maybe 10 minutes, maybe 15).
We also need the possibility of having 100+ people on servers because the number of vehicles depleted the possible infrantry squads to unsustainable levels.