It would be a nice feature to be able to record all buffered content. When I had Dish Network, you could rewind all the way back to the point where you started watching that channel, then select record to start recording from that point. Being able to rewind to any point and start recording from there was a nice feature that I wish we had.
An older DVR (HDRW-720) that I had many years ago would automatically get as much as it could when selecting a program to record. If you have been tuned to channel 5 since 11:45 and you clicked on record for a program at 12:15 that started at 12:00, it would grab the entire program. If you had not tuned to the channel until 12:05, it would grab it from 12:05.
While I really like my Tablo, I do miss some of the features from previous DVRs. The buffering in the HDRW-720 was, in my personal opinion quite awesome. It defaulted to 4 hours and was adjustable to 6. It was also the only DVR I have personal experience with where the buffer was maintained during channel changes. Every DVR since that one resets the viewing buffer when changing channels, the HDRW-720 did not.