In Texas we they love to use the chip seal pavement (it is cheaper) and I have felt rattled on all carbon too. I actually felt my old steel bike absorbed better but then again Cannondale (my current bike) is known to be some of the stiffest bikes in business and stiffness negates some plushness. I had an aluminum bike when I commuted, hated the feel and the ride felt extremely harsh. Overall unless I could get titanium or steel, I would go carbon.
I think the Ruby is a slightly less aggressive set up than the Madone, you may find this more comfortable. At least this was true when I looked a few years back, I am not up to speed on the 2012 versions.
Amanda
2011 Specialized Epic Comp 29er | Specialized Phenom | "Marie Laveau"
2007 Cannondale Synapse Carbon Road | Selle Italia Lady Gel Flow | "Miranda"
You don't have to be great to get started, but you do have to get started to be great. -Lee J. Colan