Thanks Cyclezen,
Also, I believe the Roubaix has evolved a bit since '06 and possibly redesigned for '11 or 2012...can't remember, but no doubt Specialized is always tweaking the design even though the basic comfort geometry hasn't changed. The new SL3 maybe on a par with the older Roubaix Sworks...not sure. Anyway...was thinking that I principly ride on poor surfaces...maybe consider one...or a Cervelo RS. Since I still ride primarily paved road...but bad paved road...I have resisted going with a Cyclocross bike. I have a 29er set up for road riding which I go to when I want to ride a bit more upright.
Wheelset stiffness does change the landscape a fair amount as you say.
Thanks for sharing your experience.