The RS is a great bike. I got one last year and I love it! I came from a Trek Madone 5.9 and the Cervelo blew it out of the water in terms of comfort and stiffness (in the bottom bracket). The madone handeled better, but not by a huge margin.

There is a reason why so many RS owners are coming here and singing it's praises. The bike really lives up to it's reputation!

I have not rode a Look 566 but I have taken the Roubaix out for a spin and a Synapse and to me at least the RS was far and above them both.