What are the use-cases for step-size? What 'd be the expected behavior when such parameter is mapped to a midi CC?
One "difficult case" is BPM controls, people often use a "round" bpm number, below 40 does not make much sense but an upper limit of 40+127 (when increments are mapped to midi CC increments) would be 167 bpm, too low as an upper limit.
Avoiding parameter re-computations in dsp code is certainly a goal, and frequently used, but currently not very flexible or documented well. Also UI (unit) values are not flexible in object configuration.
There are multiple things that I consider refactoring about parameters, sub-ranging for midi-mapping, inlet-parameter duality, user-selectable ranges, but these changes needs a lot of care, potentially conflicting requirements etc. First priority is going from the current 'test' releases back to a stable mainstream release...