Bottom line, the frame is shaped that way to be more aerodynamic, Trek didn't just decide to make it look that way for the heck of it. In the wind tunnel it was proven to shave time on flat courses, now out on the road, who knows. There are no problems associated with the shaping of the seat, top, and down tubes, the Team used them in 2004 and a couple used it in 2005. Personally, Lance did not care for the bike in 2003 when it was built for him to replace the 5900, so that is why Trek created the Madone SL and SSL, and SSLX, which was new for this year. If I were you I would see if you can ride the frame, it is a racing frame, and it is light, yet pretty stiff, It may or may not be stiffer than the SL, but I've seen reviews that the SL is a bit more compliant on the road. That is a good deal for the frame and if you like the feel of it, I'd jump all over that deal in a heartbeat. In the off chance something goes wrong with the frame, with the great warranty Trek has it will be replaced. Enjoy.