Brilliant technique – simple and easy 🙂 However I am wondering how you configure your pen (when you use it). I have a wacom and the pen has a rocker switch – the bottom I have set to Middle click and the top to CTL.
This means that just by using the pen I can rotate around and pan (with the shift key held down). When painting I can easily switch between the two colours as you have suggested.
It is a little tricky when changing my view, but very workable. Do you have a better setup? A little description of how you work with your pen/tablet would be invaluable.
(btw I am just talking about texture painting here, I still use mouse and keyboard elsewhere)
Cheers