Their handling is not THAT different. The feeling of the steering is a bit numb on center and not nearly as quick as a Zs (ie as close ratio). The M3 does feel a bit more rigid but hey it is a lot newer. Yes at high speeds there is something more stable about them but it is not that different.
Fill out profile - I'm curious what suspension you are running and especially the most important things .. tires. People often drive a newer car on newer Potenza S-03s and say it feels better than their Z on Kumhos (I realize you are smarter than that .. just a point.)