How's the brake tracks on those carbon wheels looking? Would your friend be willing to help you with warranty if something covered by it happened to the frame (if he's the original owner)?
I would get the S-works if the price is right and condition is good, but I'd be hesitant to spend close to price of new Scott Addict RC40 for one, when I can get this brand new instead at 7.1kg:
https://www.giant-bicycles.com/us/tcr-advanced-pro-1