I'm still looking for the perfect solution for my game, I've gone through several. (assigning and sending armies on an isometric map with pop up windows)
Having the screen center on the cursor was prettiest, (scrollto the mouse each tick) but was annoying when opening and closing windows because the screen would snap to the cursor location. (letting the screen scroll under the windows made you feel dizzy, so it locked with them open.)
Touching the edges felt logical, but felt jarring because it didn't ease in and out like I wanted. Plus, if you played in a window it would stop scrolling if your cursor ventured over the edge.
I also used the invisible sprite with scrollto behavior, and had it chase the mouse rather than teleport. It still moved too much when trying to work.
Right now I have it scrolling a speed set by the distance from the edge, but it's annoying because you accidentally scroll the screen when trying to click something near the edge, and it makes you miss.
I will probably end up with almost touching the edge adds to a variable, and the value of the variable determines the speed of the scroll. Still have the problem of the cursor venturing too far and stopping though.
Edit: Just stepped back and looked at it fresh because of this thread, and I think I have a different direction. I'm using the Touch drag demo for another game, and it works fine for the mouse as well. You click an non-clickable spot on the map and pull it to move it.