Okay, cool. Thanks for the input, bawareca. Looks like I'll be visiting one of my local dealerships to test drive cars with both engines, in order to get a better feel for them.

You are right about the M54, it definitely feels like it has plenty of torque off idle and really starts to come into its own at about 2000-2500 RPM, then pulls hard to redline. While I'm sure that the N52 is actually the faster motor when pushed hard, it all depends on where the torque hits as to how "streetable" that torque actually is.