If you are interested in the technical details of how powerline broadband modems work the paper linked below provides a nice overview. We're using the 85Mb PHY version which really means about 30Mb of useful bandwidth. We considered the 200Mb version (65Mb useful) but we don't think it is worth the added cost for our application. The only time you'll notice the peak network speed is when you are copying music to the nodes. Once the music is in the nodes there is plenty of bandwidth available to play it.

The bandwidth of powerline modems is shared with your neighbors on the same power transformer, usually not more than five homes. This could potentially be a problem that will be examined with field testing. The load caused by bulk copying to the nodes can be controlled using QOS. We don't think the shared medium will matter since music doesn't need a lot of bandwidth to play.

Intellon HomePlug AV White Paper