When riding with a Pace Partner it would be helpful to know the distance ahead or behind you are from the Pace Partner and the Pace Partner’s speed.
When riding ahead of the Pace Partner it’s distance is usually visible, though not always. When ridding behind, its just a guess.
Knowing the Pace Partner’s speed would be helpful in adjusting my effort to stay near the Pace Partner, either how hard I need to work to catch up or how much I need to back off to allow a catch without getting blown by.