Let me add my frustration to this thread.
I really was expecting this feature when I bought the Tablo (new user as of Sept 2016). Like any other DVR, this should be standard functionality.
I am debating returning the Tablo and going HDHomeRun with Plex DVR, as even in their first launch this simple feature was included. Not to mentioned NextPVR and other DVR applications have had this for years.
It made me ever more angry that this has been supported in the firmware for over a year and 3 months (July 2015 comment by TabloTV as reference), without any movement on the frontend. What are we paying for?
I would highly recommend Tablo re-prioritize this request and tie up the loose ends of having the code working in the firmware but not accessible to your end user just because your graphical team "hasn't gotten around to it".
Like others have said, simply allowing it to be set in the WebUI is great, as this is a setting that wont be changed very often.