We use an 21.5″ iMac running Wirecast to stream our church services. We have two FW devices running on the single FW800 bus of the iMac. 1st device is a GrassValley/Canopus Twinpact 100 A/D Converter to push out lyrics and scripture verses and the second is an HPX170. Both devices are visible and we can switch between the two. I haven’t researched multi-port FW hubs two run two cams but thought I would share our experience with you.