I have a 2003 Zurich built up DA components. If I was forced to choose which one of my 5 bikes to keep, I'd really be torn between the Zurich and my Merlin. (Well, not that torn, but I do like the Zurich very much.)

$500 might be a little high for a 2 year old frame/fork/headset combination. I bought a new '99 Lemond Malliot Jaune new in 2001 for $400, and it has a better fork than the Zurich.

Assuming it's the right size for you, I'd offer them $400 and see if they take it. If they won't budge, see if they'll throw in something you need.

I not familiar with your components, so I won't speculate if there are any issues with them. The seat tube does not have a braze-on for the front derailleur, though.