I use Downcast, which supports AirPlay natively in both the iOS and Mac versions. Downcast is one of the few that has the 1.25 playback speed I prefer -- and it works with the ATV4, as do all the other speed settings.
I am using PocketCasts, so the lack of an app won't be an issue for me. However, the Apple TV 2 and 3 will not play anything faster than 1X over AirPlay. I am hoping that the 4th gen will.