If you're not happy, don't buy it!
I had an 06 E90 330i from new, and it never made any crunching noises for sure.
There is a slight throttle delay as that N52 engine is a throttle-less design with Valvetronic, so you don't even have a throttle / butterfly to rattle.
The delay is only really noticeable at low revs if you plant your foot hard though.
E63 AMG on the way