i'm using Apple TV with Infuse for stuff from the NAS. plus apps for Prime, Netflix, disney, iplayer etc. i use it for everything, i never use the TV interface at all.
originally i had it running through the AVR, old Denon 2311 at 1080p. Everything was perfect. Frame rate switching works flawlessly, so the TV always refresh rate always matches the fps of the video. I cant bare it all juddery playing all 24p content at 60Hz, so its a big thing for me.
Then i got a new TV. kept it at 1080p for ages until i got the new tv unit and put the cables in the wall etc. My AVR doesnt pass 4K, and also doesnt have eArc, only ARC, so i use a device that connects to the EARC out of the TV, strips out the audio, then i put that into a regular input on the AVR. it works pretty well, but i need to reboot the device sometimes. i suspect if i powered it down with everything else, rather than just keep it powered all the time, then it may behave better. for now its better than buying a new AVR that passes 4K. My only gripe with the Apple TV is that is doesnt bitstream audio, it decodes it and sends it as PCM. It all works fine, and sounds great, but you dont get DTS-HD etc appear on the AVR.
In doing all of this, ive had zero audio sync issues.
i use a harmony remote for everything, but the Apple remote is a nice little thing, and seems to just work to control the volume of the AVR without any issues.
I am not an apple guy. i had an ipod years ago, and now the Apple TV. if your an apple guy, i suspect it works well with other apple kit.
i previously used intel Nucs with openelec/librelec. it worked really well most of the time, but the Apple TV is spot on. i'll never go back to anything else now... they had better not mess it up with an update or something.