[usrusr]

Arguably dead weight ballast scaled to the same fraction of total weight would be more fair than unburdened runner vs horse+rider, but if you expect the human to carry another human (but not the horse to carry the equivalent of another horse) you might just as well go full symmetry and require the human to carry a horse. In this variation, horse would lose to elephant.

[de_watcher]

I thought more about the ability to transport one human.