You cant go wrong with either one. You will generally shoot the one that feels best in your hand the most accurately. For me that is the Sig. Keep an eye on the ads here. You can pick either up without too much trouble.
While I am not an LEO, I have both the SW 642 and the G43. I find myself carrying a smaller BUG type of gun instead of the mid size. While I like both of them, I find my self leaning more toward the G43 all the time for size and capacity.
Nice job. It is fairly rare that they would actually listen. Most of the time their minds are already made up based on liberal media and they have no desire to actually hear what you are saying.
+1 on the Pachmayr's. I didn't enjoy shooting my 642 at all due to recoil until I switched out the standard grips for Pachmayr. Now it is not bad at all. My father has one with the CT and it is better than the standard grip with the benefit of the laser.