Butch Curry has been hosting mapping podcasts on his site and I believe some of them demonstrate uses (and the usefulness) of that technique. If you can afford it, you might want to look at getting a writing tablet (Wacoms are supposed to be good, but they range in price from $500-2500. I can't remember if its Pyrandon, RobA, or another user, but I do know there's at least one person on this board who uses a tablet.)
If you are comfortable with the method you use, then by all means stick with it. It just seems odd though to be drawing out multiple layers when doing it digitally would enable you to manipulate your images far quicker and assemble them in a shorter amount of time. There is a definite expense and a learning curve to going digital, but there are quite a few folks here who would be happy to help you out with advice.