I still ride my Zipp2001 and have found that you have to have a fairly smooth pedal cadence because the bottom bracket moves around so much, especially on hills. Sitting on a trainer is the best way to see this. Also, my front wheel seems to move back and forth slightly (and the headset is correctly put together) because of the flex in the frame. Having said that, I still won't trade or sell this bike. People have emailed and called me for a price. It's still fun and fast to ride. I say keep it and if you really feel the need to get a new bike, don't sell this one. You might be surprised how often you will come back to it. Even with it's weaknesses.

PS: the links below are old and do not work. I'm hoping to have an updated link soon.