Kerbal Space Program

What Happens:
When COM is lower than Centre of Thrust, the Yaw & Pitch Axis controls become effectively reversed. Rocket becomes uncontrollable without reversing all controls, and PID controllers like ASAS cannot function correctly.

What's really happening:
Engine gimbals seem to have no awareness of their location wrt COM. They continue to react to commands as if they were at the bottom of the rocket (below COM). But using the same steer direction at the bottom of the rocket, becomes a push on the nose of the rocket in the opposite direction than intended when placed higher than COM. (Gimbals may be working as programmed, but not as player-engineer/pilot may expect or intend)

How to reproduce:
Build any rocket with COT (Centre of Thrust) higher than COM. Attaching craft file as an example.
Launch from launchpad and low thrust to mostly hover.
Attempt to use yaw command to left, and note craft will yaw right instead. (Action of gimballing engines is also visibly in the wrong direction to "push" top of rocket in the intended direction)
Attempt to use yaw command right, and the craft will yaw left instead. Similar reversal will exist on pitch axis as well.

Suggested Remedies:
While specific tuning of various controls in the VAB may be a future feature, fixing the bug right now could probably be accomplished simply by making gimballed engines aware of the COM, and steer accordingly (reversing pitch/yaw vector if above COM). Expect upcoming wheel steering logic could be leveraged.

Notes:
Already have seen plenty of vehicles designed as skyhooks. Pending addition of Rovers will likely increase frequency of vehicles which have high mounted thrusters and a low COM for dropping payloads.

No effect on Yaw, since Gimbals have no roll authority yet. However, even if added, expect roll should not be affected by COM/COT relationship.