[ailurux]

I find that the pressure makes less of a difference than the angle and surface area of the finger/thumb making contact. If you find yourself needing to apply a lot of pressure, it might be that you need to adjust the angle. Ie, the tip of an index finger pointed straight down is basically the worst case for it, and will require much more pressure to register the touch than using a flatter angle with the pad of one's finger or thumb. The touchwheel is capacitive, and not pressure sensitive, the reason pressure might make it seem more responsive is because when you press your finger into it, its got a larger surface area making contact than a light touch.

Of course if the sensitivity seems really off even with a flat touch, then it might be an issue with something else, so please let us know if the above tips help