I went from a 2015 S-Works Tarmac to a SL6 and the difference is astonishing. They claim it’s as aero as the previous Venge, but the first thing I was really impressed with was how much faster it was into a headwind. I was just able to hold more speed. And as it’s so light, uphill it’s angood deal faster than the old Tarmac.
I’ve ridden the Cannondale, and the one thing I liked more about it was how planted it was going downhill. However, in every other way I find the Tarmac to be a far superior bike. If it were my money, I’d consider the Tarmac SL6 as a serious contender too.