I love my 04' firenze. If it were this year's model, with 105 components, I might go for the Felt. But with ultegra components and a pound a half difference, I'll just keep it and save the $500 and spend it on a pair of krysiums to replace the cosmos and you'll drop a pound right there and get to keep that sweet titanium ride.
You sure he's not trying to talk you into the american bike corp's trade-in where they give you back approx. half the value of your 04' frienze for a new bike?