If I'm using a camera stabilizer (steadicam) or doing a slow pan should I disable the cameras optimized image stabilization? Will it improve the picture in any way?

Generally when using off camera stabilization such as a tripod or crane, it's best to turn the Optical Image Stabilization off. I would assume the same applies to a steady cam.

I have my HV30 on steadicam merlin. I left the OIS on even on tripod. =)