I know you’re probably here to read all about how the 2011 Jaguar XKR Convertible stacks up against other six-digit luxury sports cars, but I’ve got a confession to make. Before we get down, dirty and up to our elbows in power figures, you need to know that this is my first real brush with luxury performance of this caliber. As we speak, the ruling houses of auto journalism are likely sending laptop-wielding assassins my way for breaking the seventh...