Originally Posted by Remonster
The 6 was a very nice engine, I've had two E90 328is over the years and now we have an F30 with the new turbo 4. The N20 is more powerful and more fuel efficient but it has a little bit of turbo lag and it's quiet, plus it doesn't sound all that great when you can hear it. The N52, on the other hand, was responsive and had a very sweet growl plus it might have been the smoothest engine of all time.
I can definitely understand why someone would prefer either engine over the other, I'm not sure which one I like more to be honest. I think I favor the N20 just because of its surprisingly huge low end torque, the N52 below 4,000RPM feels downright slow in comparison.
I've got a Z4 3.0si and I love the N52. I agree with what you had to say above.
I had a F30 on loaner when I had the Z4 serviced. Honestly, the N20 didn't feel right. It felt like it wasn't as responsive, didn't have as much power and the sound out of it was too tame. Definitely the F30 is for those who just want a BMW. For a car enthusiast, it might be a disappointment. I don't consider myself a BMW "expert". As someone new to the BMW world, the N20 is a disappointment.