Only one thing really needs fixed - the way the hi-hat controls.
The problem seems to be when the pedal is depressed and the hi-hat pad moves away from the magnetic sensor. The space in between being fully open and closed is too hard to control.
When I play, keeping them tightly closed is easy because your foot is resting on the pedal. Fully open and your foot is off the pedal, and therefore its easily controlled. In other words,
the sensor distance from the pad is constant because of a constant pressure or a constant lack of pressure.
However when you want to have the hi-hat say, a quarter open, or half open, or three quarters open, it is very difficult to keep the sensor distance correct to keep that sound, because your foot is going to move a little as its not resting on anything. In other words,
the sensor pressure (naturally) does not stay the same.
Add to that, the sensor is saying the foot pedal is moving a little even though it is not, and I guess that might be the sensor detecting the wrong distance to the pad because the pad has been hit, and the distance or angle of it to the sensor has changed slightly.
I think that these two things basically mean your foot has a lot of trouble picking the right amount of pressure to give you a consistent sound. This is really hard to explain and I hope others know what I mean...
So I think of one way we could approach a fix - please be aware that this idea might be UTTER RUBBISH cos I have no idea about these things but here goes:
Instead of calibrating the hi-hat sensor for being closed ONLY (and I assume that it then just measures the distance away from the pad after that), why not set the sensor once for fully closed, then, choose how many 'progress squares' (the squares under the UNIT/HI-HAT/PEDAL INDICATOR that show it going from closed to fully open) you want it to move and set the right distance again on the hats.
For example, at the moment the 'progress squares' move far too quickly even though I only move the foot pedal a short way. So I would be able to tell the module, 'ok, when I move the pedal a quarter inch, I want you to move to 4 'progress squares', but I don't want any more 'progress squares' until the pedal has moved another quarter inch. Like a dead zone where slight movement is allowed and the sample will not change.I don't know if this is possible or even sensible

but it might be a way for people to have a lot more control over how the hi-hat plays...