I don't use a vol pedal on my acoustic board, but do on my electric board. So the short answer to you is: they all vary! Each volume pedal's travel/volume response differs, not to mention there are those that suck highs and others that are more transparent.
You really have to try them to see what works for you. But like you, I am not satisfied with my Morely Mini where most of the volume ramp is near the heel down, so swelling smoothly up to full vol takes some practice ...not at all what I would call "good" but just barely usable. I also think the mini pedals will suffer more here as the larger pedals allow for longer treadle throw, which likely will offer smoother, more natural ramping. If I had more room on my pedalboard for a full-sized unit, I'd do so, but alas must make do with the mini purely for space considerations. Post back if you find one you think works well, would ya?

Edward