JPNZ:
Watched the first 2 hours of the test on SSN on my ipad in bed last night. No buffering and no stalls. Interesting as my ATV is hardwired yet its buffers a lot
I'm using an Apple TV 4th Generation on Wifi and its been Flawless - I've watched every canterbury game in Super Rugby Trans Tasman and about half of the Aoteoroa ones.
Before that I used an i5 NUC in browser and had a few strange glitches. Overall the video quality on the Apple TV is far better - Its like they've used a better codec as the motion is smoother - Not sure if its the Data rate or if they are using HEVC/h265 rather than h264 or what but I'm also finding TVNZ Ondemand a lot better quality on ATV aswell. In part its probably just that they are putting more development into Mobile, Chromecast and ATV than they are in playing from a PC.
When I say I'm wifi my wifi is two long range Unifi AC access points and my 100/100 Fibre is the bottleneck as the wifi give better speed than that almost everywhere in the house. As you say though, on Ethernet it should be even more reliable - Just stating that although I use Wifi its not your crappy ISP provided all in one device.