Hmmm... As I said before I have a 4x5. When I need to trace, I scan the image and do the tracing in Photoshop. I don't se any benefits doing it on the tablet. If done on the tablet you have to look down on the tablet, trace, check the result, maybe delete or edit, look down on the tablet, trace, etc..... When done in Photoshop (or whatever you use that has layers or something similar) you could trace an a layer on top of the layer in witch you put the scanned image. That way it's easy and fast to work on a line until it looks like you want. You will probably get two or tree tries at a line on the same time as you get one try tracing at the tablet. You can also observe and correct for wrong mouse pressure (maybe to wide or maybe to opaque line) as it happens.