I guess it all depends if the Bravia core app does some sort of speed test in the background before deciding what content to push. I wonder if it even makes it clear if people are getting the full quality stream or not...I'd imagine 100mb Ethernet would be sufficient, the 126mb recommended I imagine is to include for overheads for say if someone else is using the broadband in your house, or your devices are downloading updates etc and eating into the bandwidth.