Originally Posted by botto
whichever bike is the best overall package.
Here is where things get tricky. The R5000 has a Dura Ace package, and the Six 13 has Ultegra. Both bikes have the same Ksyrium Elite wheels, weigh about the same. The Six 13 has a supposingly more comfortable frame with better stem/handlebar/seatpost/crankset.
The R5000 on the other hand has a lighter frame, and is more stiff for sprinting.