Convert Standard Assets AICharacterController for Walls/Ceilings

Hello,

The new NavMesh components are great. But I've run into such issue - I can make a cyllinder climb wall and ceilings (just planes oriented at 90 and 180 degress), but when I use AICharacterController from Unity Standard Assets it cannot move properly, probably because of physics.
I've used NavMeshLinks for moving from surface to surface properly.

Gravity on:

Character pulled down to the lower edge of NavMesh, can't move up.
Gravity off:

Character moving very slowly and jittery, moves legs, sometimes "flies".

How to make AICharacterController controller (Ethan) able to move on walls and ceilings with physics normally, just different "ground" (and gravity) orientation?
I've tried to add force pointing down to character model but it still didn't help. AI character controller doesn't move properly even when gravity is disabled in his Rigidbody component. He either moves very slow, or doesn't move his legs, or falls down, etc.

I've added this code for "click to move" in Update() of AICharacterControl:

Code (CSharp):

1.        private void Update()
2.         {
3.             // My addition
4.             if (Input.GetMouseButtonDown(0) && !Input.GetKey(KeyCode.LeftShift))
5.             {
6.                 var ray = Camera.main.ScreenPointToRay(Input.mousePosition);
7.                 if (Physics.Raycast(ray.origin, ray.direction, out m_HitInfo)){
8.                     agent.destination = m_HitInfo.point;
9.                     //target = m_HitInfo.transform;
10.                 }
11.             }
12.  
13.             if (target != null) {
14.                 agent.SetDestination (target.position);
15.             }
16.  
17.             //My addition
18.             agent.SetDestination(m_HitInfo.point);
19.  
20.             if (agent.remainingDistance > agent.stoppingDistance)
21.                 character.Move(agent.desiredVelocity, false, false);
22.             else
23.                 character.Move(Vector3.zero, false, false);
24.         }

Is there some simple way to fix it?
I'd appreciate any help.

PS. A request to Unity team - could you please update the AICharacterController for differently oriented surfaces now that they're part of the engine?