Riding the CAAD8 you might get the wrong impression of what a modern aluminium frame feels like. I have been riding my CAAD8 for 3 years now and have been very satisfied. The BB stiffness is impressive (mine is the BB30 version), but it lacks some stiffness in the headtube area. It's also obvious when looking at the small square section of the top tube. The comfort of the rear triangle is great on this frame and can't imagine more modern frames could improve on this. On my first rides I often though I had a puncture, it was that confortable.
I did a spin around the block on the CAAD10 last week just to adjust the gears. Just in my everyday clothes and shoes it was obvious that the headtube stifness has increased massively. It's no big surprise when you look at how massive the top tube and bottom tube intersection is. I'll measure the top tube, but you are looking someyhing like 4 times the square section of the CAAD8. What that transfers to on the road I'll know when the snow has gone.
I'm the head of marketing at DAA Israel, we represent Shimano and many others components and accessories brands. The bicycle brands we represent in Israel is Cannondale, Orbea, Niner and few more. If I'll find the case frame good for me, I can take caad10 frame. I still hasn't ride the Evo frame for real