I personally tried out the Tarmac & Roubaix (in the same day) riding on some of those crappy chip seal roads. The Roubaix soaked up a lot of the vibration, BUT....the Tarmac was FAAAAAST! I assume you can guess what I purchased.
See below.
My suggestion is to just go try them both out for yourself. You might love one or none, but at least you'll know. Good luck on your quest!
I aspire to be...the best I can be...the best I've ever been!
2011 Tarmac SL3 Pro Sram/"La Sombra Blanca"/Specialized Jett