Just some suggestions on how to make them better and more useful.
1. We could give gyrocopter variants (both) the ability to fire-whilst-moving.
2. All gyrocopters and bombers should probably have AP weapon strength since I believe they use their rotors to attack and they are whirling metal blades... Plus, their WS could probably be higher.
3. We could even give them a bonus vs. infantry in melee and lower their MA slightly to compensate. Their blades are the type of weapon that would be especially effective (in theory) against infantry and not as effective against larger entities that would be harder to cut through due to mass.
4. Give the gyrobomber more ammunition. They go through their ammo surprisingly fast if you can actually keep them alive...