I had to consult DH on the Six13. It is aluminum so it will be slightly harsher ride than the Ruby. But with the carbon seat post, front triangle and fork I don't know how much the aluminum will come into play. Cannondales are excellent bikes, so are Specialized and from what I hear both are excellent on warranties if you (hopefully don't) need them. I don't see how you could be disappointed in either bike, if you like the fit of the Cannondale I would go that way.