Will using a pannier rack mounting kit damage a carbon frame Axiom vs Tubus
I would recommend getting a second bike for commuting. The Specialized Roubaix is a racing machine. It would also be foolish to leave it locked outside a shop (in case you considered doing that).

Most likely you will void the warranty by using clamps on seat stays. To get that low weight, carbon frames are strong only in certain directions and may be relatively weak in others.