Interesting reading from the Roon forum. Thanks to @deuch for the link.
I briefly have compared WiFi and Ethernet operation of the Aries and Aries G1 and never heard repeatable differences in sound quality. I will say, though, that I am not the type of person who can listen to the same track over and over again, focusing on possible deltas. When I try, my head feels about to explode, and I have a powerful urge to do anything else.
My interest in this came after a discussion elsewhere. That, and having no obvious way to indulge my tweaking urge without spending a lot of money. In the frame of audiophilia, Ethernet isolators are relatively cheap – though perhaps the money would better be donated to charity.