I have never felt comfortable with the idea of using a saw unless it is a jeweler's saw. Trouble is, you can't use one on track alread in position...it needs to be clamped in a vise. So, I would use a Xuron Rail Nipper held vertically, although that has risks, too. The beveled inner face of the jaws tends to force rail on that side away from it, which will disturb track for some distance in that direction, or potentially so. A fine diamond cut-off disk can certainly be used, although you'll want steady hands and to use the flexible extension in order to get it vertical.