There are many variants in PSTouch that can be edited by typing the number as an alternative to using the slider, and that is very convenient. However, two of the most common variants, the brush size and hardness, can only be adjusted with a slider. This is very annoying when you are trying to hit a specific number, eg. if you have already made a stroke and you want to paint further with the same size after you have changed it.
To make it even easier to change the small numbers you could add up and down arrow keys, so when you have hit 53 with the slider you only have to tab three times to make it a nice 50.