No rattles or repairs. I've had it on the track twice. Each time was a full day and there is still life in the P zeros! The car loves to be driven on the track hard. No break fade or overheating, it just wants more! On the street it is not high strung or difficult to drive but very smooth and easy. The stability control system in track mode is so liberal that I can't tell the difference from track mode and full off! The car sticks like it has glue on the tires but it does have snap over-steer and needs to be driven with respect if you intend to drive with the traction control in track mode of off (not!). The rear end can be very light and twitchy but that is part of what makes it exciting!
A couple of years later:
I traded the XKRS in for an F Type R. The F Type R is a far better sports car but the XKRS is a great GT car. I miss the XKRS. The back seats were very convenient. I never had a problem with the car during my 3 years of ownership. The problem with the XKRS is the snap over-steer. If you leave the stability control system on the car is perfectly safe and fun to drive. Jaguar has a way of making their cars feel special. When ever I get in and start getting the car ready to drive I can feel my heart step up a beat with excitement. It's really hard to put your finger on what exactly makes driving a Jaguar exciting. My Father's BMW 740 didn't do that for me and neither has any other car that I have driven. I guess that's why I keep buying Jaguars. A neighbor from down the street asked me if I worked for Jaguar because of all the different Jaguars that he has seen in front of my house. I said no I just like them.