@Jestep What you found in the user guide is certainly relevant, but mostly for tuning to two channels at once. For example, if you to tune to channel A first, and then switch to channel B, the Tablo will store channel A’s data for up to an hour. In regards to your original question: the Tablo should be able to sit on pause for several hours - I’ll have to ask one of the engineers for an exact number.
To expand, your Tablo can play Live TV and still enable you to pause, rewind and fast forward everything you’ve watched up to around 10 hours. I’ll have to see if this works the same way when paused.