I second that, I was not impressed with the quatro. The mach 3 is the way to go. As for edging with it. I just pick a reference point along my ear and do the same thing on the other side. Seems to me that the reference point is about 1/8th of an inch high.
note, if your face is misshapen or your ears aren't symetrical, this may not work for you
probably off the original thread, but related none the less, what type of trimmer do you use? My battery is running low and i need to invest in a new one..