I have the Elite. I don't have the Wildcat.
The Elite is awesome. Very sturdy and responsive. My only issue would be that the circular disc they supply for the d-pad (it's the one you see in promo pictures) is a bit loose on the attachment. I think it's actually supposed to be that way for fighting game aficionados. The good news is that the normal cross d-pad attachment clicks on solidly and works really well.
The customizable sticks are a nice plus as well. You get three different ones for left and right sticks that comes in varying lengths and with different pads on top. They mimic the functionality of those nubby things you can attach to regular controllers for precision driving etc.
The magnetic underside paddles are terrific. I can't go back to a controller without paddles.
From what I know the Wildcat doesn't feature stick options and the d-pad isn't interchangeable. The Wildcat does have additional mic buttons on it. (Push to talk, stuff like that.) You also get grip stickers to apply to the Wildcat controller.
Also, you could check out SCUF. These guys sort of pioneered this area and showed MS that there was a market for $150 hardcore controllers.