I have no experience with the E60's, only the E39's. I'm guessing the newer models should handle at least as well as the previous generation plus a few technology upgrades. They would be heavier though. Style wise, I prefer the E39, more classic BMW look and better visibility.

As for truck v. car, I'm biased towards cars. Far better handling, ride, and fun. My X5 is really just a utility vehicle in comparison. If you're looking at either a 545 or 550, have you considered an E39 M5?