I wondered why the 7S14 had the delayed timebase and Vernier control of the delta-delay markers but this was omitted on the 7T11. There could be several possible reasons and Dennis may be able to point to the truth.
The 7S14 has a delay line so that you can see the trigger point and make accurate time measurements from the trigger to other features on the waveform. On the 7T11 in sequential scan you are looking 10s of nsec after the trigger so you largely lose any time reference from the trigger event.
Another very good reason might be that the 7T11 is already very well filled with multiple boards.