I too have both a Cooper and a 2010 Tarmac. My Tarmac 8r frame and not the 11r frame like yours is actually buttery smooth on rough roads and yet its super stiff where you feel every power stroke go directly to the rear wheel. I know the type of wheel you use also plays a part in how smooth a bike rides. I love my Tarmac, but I ride my cooper 90 percent of the time, it just seems to have that magical ride!