What's your budget?

I skimmed your post...I remember bad back...I remember you want to go fast...I remember you've avoided aggressive bikes in the past.

I say either Specialized Roubaix, Cannondale Synapse, Cervelo RS or custom. End of thread. The three stock bikes I mentioned are fast fast fast...comfy as a cadillac...and have slightly relaxed geometry. If you know exactly what you want, you could just have the customer maker of your choice just make your dream bike for you!