I really like my Craycort grate, but my OCD does get a little fired up at times. It's really nice, though, to be able to pull out 2 or three sections to allow easier heat flow inside the grill-- you can just have grates where you need them.
A downside to Craycorts is that you need to keep them out of the weather, lest they rust. Where standard Weber grates can hang up or be left out in the rain with much less concern. This might be a good reason to get another kettle, though-- as a place to keep your extra grates out of the weather. I think I'll pitch my wife on that idea. ;-)
If you haven't gotten your grill yet, though, I'd just cook on the standard grates for awhile, see what kind of cooking you tend to do and what grates will serve you well. Craycorts, for example, are great for searing but might be a hassle to work with if you do mostly indirect cooks. OTOH, if you cook many steaks at a time, the Weber gourmet system might be more hindrance than help. And remember, our grilling forebearers did everything on plain ol' non-hinged grates. They seared with *fire*, man, and it was delicious.