Setting llTargetOmega's vector to a ZeroVector no long returns it to it's last known Rotaion setting. IT just stops. The other problem is the position it stops on is client side. so where it sees it stop is not how it looks to others. Also when it has stop rotating it look like it has acctually update the rotation but it didn't. Two people will see two differnt numbers in the rotation parameters.
On the plus side this may work out better. if you call a stop to rotation and then calculate where it will be when it stops the SetRot can now be called after the TargetOmega rotation stop. Although you now have to take into account the Delay with SetRot which will a slight stop in motion before it changes direction.
On the negative side many door script are setup to call to rotation during the omega rotation.
EDIT:
Target Omega still does not work on objects after they have been copied if it does not use teh SetText hack.
EDIT2:
After playing with more the method of movement works out much better. espeicially on child prims. No longer get a jumping motion. Calling the SetRot after the Stop of rotation for its final Rotation tends to work much better. And Now FLog! golf power/accuracy meters works muck better