Smokin' is right. I started with an 008 smoker with the normal grates. And I was rather anal as to getting the grates very clean. Eventually they started to look like copper, but I am not sure what the metal really was... but the plating had worn off.
I sold the 008 when I upgraded to an 055 and again had the normal grates. This time I would just stick them in the dishwasher which loosens and removes most of the food. Then a quick and short scrub when they come out to remove any leftover food particles. The grates aren't shiney, but who cares??
At some point, I bought the stainless steel grates but I have yet to use them. If I ever do wear the plating off the current set, then I will switch to the stainless.
Short answer: You don't need the stainless if you don't abuse the standard grates.