When it's really snowy and slushy out and I track snow onto the factory mats, it tends to form little ice spots there as it melts with the heat on and freezes when the truck sits. This is usually right where my driving heel rests. Anyway, I have a set of Weathertechs on order too and I just cant see that problem occurring again. Ice is much easier to crack off rubber than it is to pick it out of carpet.
Even if you do track lots of snow and crap in, I'm sure you could push it out of the way and still have the mat contain it. There's a guy here who caught an entire cup of coffee with one!
*edit* btw Tacolot, after all that I forgot to ask..what area of town are you in?