Hmm..
Well, my silver Taurus is an '02 and the paint has lasted just fine. It's also a metallic. When people refer to metallic, they are usually referring to a shiny, glittery 'metal flake' in the paint, not just certain colors. I assume that's what you mean? You can also have a red or white metallic, as well as a non metallic.
I don't think metallic paints, or paints of any particular color are any less likely to last. Sounds like one of those "I had a silver car that faded so that must mean silver doesn't last long" stories. But of course there are variables, like type of paint, manufacturer, what year it was produced, how it was stored and maintained, etc.
I don't know about maintenance or anything being different, but I know it hides defects really really well. Amazing how dirty it can get (especially in the winter) when it comes time for the weekly wash, and it still looks clean! That is to say, I pull it in to wash it, it looks clean, but I take off tons of dirt and grit. Silver hides dirt, and it really hides scratches and imperfections extremely well. It's one of the 'lowest maintenance' colors, IMO, just because it hides flaws well. As opposed to say black, which isn't actually a color it's a full-time job. Black shows everything. (But I love it!)
