It depends on why you bought the XKR in the first place. For me, a Jaguar tells on-lookers that you're not a "me too" person. It doesn't matter how powerful your MB or BWM is, the marques are very common and too much resemble their lesser brethren. Jaguars don't have "lesser brethren" with the death of the X-type. They are like Porsches in that regard; you can go several days without seeing one at all, much less an XKR.

I would probably go for another XKR in your position, but would also consider the Aston Martin, Maserati and perhaps a Bentley. An Audi R8 is also a unique car and you may come out ahead in the reliability and resale value side of things with that selection.