Chrysler has made a huge jump in overall quality with the introduction of the SRT brand. American car companies are really changing the rules of the game at this point. I don't think you will be disappointed, but you will lose the agility of the M3. SRT300 should be compared more to the 550i.
2014 Audi S6 * 2015 Audi S3 * 2015 Porsche Cayman GTS
Former 2011 BMW M3 owner