In theory, ArtRage has as many levels of pressure-sensitivity as the device can support.
Technical bit: When ArtRage starts up it asks the tablet driver whether is supports tilt, rotation, how many levels of pressure, and several other things. Then, whenever packets of data come in from the tablet, the pressure value is divided by the maximum range of pressure to get a value of '0' (no pressure at all) to '1' (maximum pressure), and everything between. The result should be the same regardless of how many levels of pressure the tablet device supports. So if your tablet supports 1024 levels of pressure, so does ArtRage. If your tablet supports 512 levels of pressure, so does ArtRage.
Then we take that value and depending on the tool we affect the profile curve of the pressure range - for example a pencil needs a correspondingly harder pressure to give a solid line than a crayon needs. This affects the 'feel' of the tool.
Which is all good in theory, but we're also competing with the electrical properties of the input device, conversion factors of each manufacturers drivers, and any pressure scaling or preferences the user has added to the device setup.
So... Because we scale pressure non-linearly, some devices can give quite different results between ArtRage and other applications which likely use a linear pressure gradient.
Here are several things to try to get the 'feel' you like with ArtRage:
1) Make sure you have the latest drivers for your device. ArtRage expects certain features of tablet drivers to be present and may have issues with older tablet drivers
2) Some tablet devices ship with an application called 'Pen Commander' which can do evil things to tablet input data. Remove or disable Pen commander.
3) If your tablet device driver supports preferences for individual applications, change the pressure curve for ArtRage to give the feel you like.
4) Inside ArtRage, you can adjust the pressure sensitivity for each tool using its pressure radial control.
After doing the above, test your results in ArtRage: Take the crayon tool at 50% size, and do a smooth stroke across your canvas, smoothly varying your pressure as you go. You should see a smooth transition between the different pressure levels. You should not see 'blobs' of pressure, or All-or-nothing pressure.
AndyRage's mantra for graphics engine code:
"Sure - how hard can it be?"