I don't know if it's a Cayenne eater.
In stock form, it's only as quick as the old SRT8. They focused on interior, comfort, fuel eco, and functionality (it can actually tow now!). Being based on the MB ML has its advantages.
It's still over half a second slower than the Cayenne Turbo, though it is quicker than the other trims.
There is a catch though. As it uses a modern big American V8, there are already several companies working on tuning and aftermarket options. I give it a couple months before companies come out with turbo and supercharger kits. As it is, certain kits might already be compatible (blowers).
I like it, though the appearance hasn't won me over yet, it still looks better than the Cayenne. I wish the interior was nicer though, the Cayenne's interior is in another class.