Was thinking about this idea for some time as well, just never posted anything about it. For instance there could be a slider for dt and ht with values ranging from [1.5, 1.75, 2.0] for dt and [0.5, 0.75, 0.9] for ht and next to the mod symbol could also say the speed.
This could also be done with other mods as well for instance hr and easy which determines how small or large the beats are or something like that.
This could also add more variability in the scores without adding new mods, although there might be too much variety that it gets confusing when looking at the scores.