My only annoyance with "Green Ethernet" things is that often they seem to work poorly.

The dedicated machine I still keep around for Windows things has two onboard 2.5GbE ports. It will apparently sometimes, even with all power saving features turned off, randomly negotiate down to 100 mbit if I leave the machine alone for a bit, and then stay at that speed forever unless I manually reset the link after wondering why transferring large amounts of data is bottlenecking severely.