I think you should try M4... (Don't be fooled by those biased messages. You have to try it on your own!!!)
Even on highway when the road condition become very rough M4 could be bouncy like crazy(under-damped)... Much less stable than my stock GSF!!!
PS: A little under-damped is good on very smooth racetracks but not good on public roads. In addition, over 99% of the time I don't track my GSF, will you?
By the way M4 is an iconic car from German. Of course. Porsche is better. But, M4 has at least 95% of sportiness of Porsche and Porsche has at least 95% of the best in the world!!!