When using shape dyamics, the preview of the brush does not reflect the accurate size of the brush. I would like to see the size of a pressure sensitive brush in real-time, so I have visual feedback on the effect of my pressure on the size of the brush.
Even when it is set to fad, pen pressure or Stylus wheel (if that is not already so), it would be great to see the brush as it will paint.
When a pressure sensitive brush is not touching the tablet, it should turn into the crosshair, as soon as there is pressure, it should be the correct size.
I always thought it was impossible of the calculations, but we have been doing things like this with the stamp tool for years now. And that feedback has made the tool extra useful.