I've been a Channels Apple TV app user for about two years.
They just released a major upgrade this week to Version 4.0
I have a 2011 Mac mini as the recorder working with two OTA antennae (Manhattan high rise building with poor sight lines to signal).
This set up serves two Apple TV 4 in two different rooms.
The system has performed well.
The developers are easy to access via their forum or Twitter.
Set up is now relatively simple and the remote iPhone and iPad apps work well.
HTH
Joe