I tend to use a quite high sensitivity for look and ADS, but it is WAY too high for piloting or aiming in-vehicle weaponry (tanks/lavs/turret MGs/tank spotter position).
If I want to use one of these vehicles effectively, I have to change all four sensitivities...then when i'm out, I have to turn them all back up again.
If there was a separate sens for:
Look
ADS
Helicopter - look (pilot maneuvering sensitivity) and ADS (side mounted turrets) options
Land Vehicle - look and ADS could probably be one option, but may as well be both like the helicopter