I upgraded to Final Cut Pro 7 and used the iChat Theater option now available. This is a great feature for us at Post Fifth Pictures because we handle a lot of work from distances. We are in California and Utah, but our work deals with Florida at times or in California while we are in Utah, and vice versa.
I tested the feature out over a wireless network, with only 2 bars on my wi-fi. I played Apple ProRes 422 HQ encoded footage, 23.98 1080p, with no problem at all. It streamed perfectly and looked like it had a great image. I previewed this feature with Cole Webley over at Saint Cloud and on his end the image looked great as well.
The image shown to your client is that of your timeline, the edit monitor. Rewind, fast forward, it moves around wherever your cursor goes. This is one of my two favorite features in the FCP 7 upgrade, background compressing being the other.