I had springs on my last 335... went with coilovers on the new one and never plan on looking back
My last car had just springs, and oem shocks so I cant really compare that to the bmw perf. set-up, but going from my old set-up to the fk coilovers i have now, I feel/have been able to throw the car around corners ALOT faster than before with more control of the car as well..