WASD is more sharply functional than any mouse pan, I should think . . . as well as being a gaming industry standard. If neccesary, edge-of-the-screen pan would be useful and intuitive, too, panning the screen when you move your cursor close to the edge.
I've worked with a few indie devs, and have learned that if possible, it is best to avoid any use of modifier keys. The majority of players will never know they exist. If at all possible, every command that isn't geared toward hardcore precision gamers should be a single keystroke, click, drag, or etc.
Not only does it make the game easier to pick up, but the controls become intuitive faster.
