Weaknesses: This was the first generation Madone with funny shaped tubing. Perhaps the round tubes of the SL are better and more resiliant in a crash. The strength of the odd tube shape of the Madone is questionable.
For charging so much for a frame the Trek crash support could be better.
If you want to ride your roadbike then consider something cheaper that does not hurt so much to replace.
This review is of the 2004 Trek Madon 5.9, silver frame.
This frame is great if you are no afraid of carbon cracks. My frame cracked in the downtube in a road crash. The water bottle holes and increasing tube diameter create a weak spot as this is where the frame cracked. The crack proceeds up to the water bottle hole and around the bottom of the tube. Trek does not warranty such a crack as it was "imposed by a crash". The best Trek offers is a minimal crash replacement.