There's always the keyboard shortcut for just toggling adaptive movement speed on and off (for when you're using it to slow you down).
I do like the suggestion of being able to specify the offsets in absolute units, rather than relative ones.
For base speed, it opens up a lot of questions. If we specify an offset (as we do now), in absolute units, depending on exos or not, it can result in a movement speed of 0 (or negative if left unclamped). I think that also wouldn't help in your case, as what I think you want is to just always start at some base "pretty slow" movement speed, and then ramp up to whatever movement speed you have access to depending on your exos.
I'll need to experiment with this to determine technical feasibility, and work out some set of settings that are not too overwhelming for players, and enable your desired use case.