@Fofer
Interesting thought. TiVo devices were designed to "always be recording." Whether it was recording a TiVo Suggestion or just filling a buffer all of the tuners were always working. There could be some value to keeping that philosophy with this.
There is no real logic to tuner selection in ADBTuner. It just goes through them in order and selects the first one that is not being used. In earlier versions I had some extra steps in place to try and keep it on one device, but that was removed to improve performance (faster to jump to an idle device then wait for the current tuner to be unlocked).
I don't have any plans for what you suggested, but it's an interesting idea.