I too upgraded from a D300 to the D800. While I don't have a Porsche, but will admit to dreaming of owning one, I do have an old car which I bought new in 1974 and still own and drive today.
The BMW 2002 is credited with inventing the sports sedan class of automobiles. While it is not a sports car, it possesses all the right attributes which led BMW to the well-known advertising slogan, "The Ultimate Driving Machine."
In 1974, I sure was impressed with the 2002's engineering. In similar vein, I was equally impressed with the D300, and now, most recently, I'm just as impressed with the D800. Here's a shot of my 2002 with my D300 in 2010.