I guess you could always factory reset the device and see if that clears up the issue. It sounds like rolling back a few version didn't do anything.
I'm holding off on a full factory reset until I hear back from tmm1 on my question if the test flight versions correspond to an exact release version, or if there are differences, as there is a lot of work involved in getting all the apps set back up the way I like them. That and I'm not sure that 1 month back of versions is far enough back to really make sure. Keeping the factory reset as an absolute last resort 
There isn't a "Load more builds" on the tvOS version, I looked for that option earlier, it must be an iOS only option.
FYI, I reset the apple tv to factory settings, only installed the channels DVR app and it is still stuttering when playing recordings. It appears there is something in that latest app store version that doesn't like the Apple TV HD or relies on hardware within the Apple TV 4K, as my 4K model is working fine with the latest version of the app.