Fragility
A lot of the problems came n board either very early, when the heat treatment hadn't been perfected (Cannondale had even bigger frame snappage problems!) or after Trek gotten hold of them and put the really silly replaceable mech hanger with bolt through the chain stay design in place. I am just building up a Pinnacle (which will get some stick) and have an Adroit race on the way (which won't-a full refurb job)