I found from the HDHomerun forums that I should update the firmware. I downloaded the latest and updated, and now I'm seeing about 14 Mbps, which is perfect. If I decide on another HDHR, I'm figuring about 56-80 Mbps of bandwidth. Since our house was wired back in 1999 with Cat-5 (not 5e), 100 Mbps is as fast as the network can run. Also, each SageTV HD extender can use up to 20 Mbps so in worst case, the network will be overloaded - for 1 NIC. Furthermore, where I want the PC located there is no cable jack so I can't create a local GigE network with the HDHRs and the PC. I do, however, have a Cat-5 run from the HDHR location to the PC location, so I can create a small 100 Mbps network with 1 NIC and the HDHRs. I can then add a 2nd NIC connected to the main LAN to handle regular network access and streaming to the HD extenders. One thing is the HDHR is a DHCP only device, but will default to a 169.254.x.x address if no IP address is handed out to it. I just need to set the HDHR connected NIC to 169.254.y.y with a subnet mask of 255.255.0.0 and the PC should see the HDHRs.
Edit: Turns out, the reduced bandwidth I was seeing was due to using VLC to view the streams. Using Sage, the bandwidth was still 30 Mbps. I have since installed the SageTV 6.5.8 release candidate and the bandwidth is now down in the 10 Mbps range.