The Neet box worked fine with the AppleTV 4th Gen for viewing Game of Thrones Season 5 in Hi-Def, very occasionally I was aware of tiny leaps, where there is a jump of maybe 1/10 of a second - only noticeable on slow scenes. During the whole season of GoT it happened about 6 times, I also had one complete seize, where sound kept playing but the picture was stuck, which required me to restart GoT. I can't say whether these issues were anything to do with the Neet extractor, or an issue with the AppleTV 4th Gen. However the issues were so small as to not cause me any problems. I'd prefer Apple to have put a native audio output on the device in the first place, it's just a faff on for customers with higher end audio set ups.
On a side note... I found the Wi-Fi connection flakey with my router, so moved to a wired network connection which worked fine. Can't get 'remote' to work with my iPhone. Found imputing characters with the remote that comes with the box an excruciating experience. I found the pricing of past content weird, 'films & tv shows', I could find most things far cheaper on Amazon, and you got a nice disc with it to give some confidence that it will be available for some time. I'm still uncertain about how long things I've purchased on AppleTV will hang around, will they be available when I upgrade to the next AppleTV... who knows, it all seems a little opaque and unclear to me.