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.
E90 330i 6MT gone. E91 335i 6MT gone. AMG E63 Estate gone. M6GC current...