I have Synology DS710+ and HDX BD-1. 1080p & HD audio streaming is smooth & stable, even though some other BT tasks are running in the NAS. I use Giga LAN switch but I think 100Base-T is good enough.
If my memory is correct, DS710+ is the fastest and quietest 2-bay NAS among Synology & QNAP. I use it for both HD movie and flac streaming, hence speed and noise level are the most important considerations to me. Yet another point is that I don't like Synology's case design in general. DS710+ is merely acceptable...