If you have a Wacom Intuos (3 or higher or Intuos Pro), you can assign one of the pen buttons to modifier alt + left click. There is a slight delay as it performs the operation, but this will allow you to color pick by hovering and clicking, allowing you to remove 2 other input functions and increase the productivity while reducing repetitive wrist motion (and associated long term strain and stress on muscles). I suggest giving this a try if you have the capability, I'm going to be trying to find a way to do this with a mouse as well (maybe with some 3rd party program).

I also suggest the ArtRage team give us the ability to keybind color picking on hover as I've described here directly from the keybindings menu (whether through a keybind or other single input press, like mouse 4 or 5 or middle mouse button).