There is a great interview with Tim and Nicole Deboom at www.beginnertriathlete.com.
Interesting, even controversial comment:
“I chose the Madone SL over the TT bike because of some weight issues. I really wanted to go as light as I could because it’s a long day out there. Any extra weight is really evident the second half of the race. I did a lot of testing and the weight advantages outweighed the aero benefits of the frame.”
So weight matters more than aero benefits?