As far as the wasted power, so again.. I don't have a 3k road bike. Both my bikes cost < 700$ to put together, and at that price the fixed gear is probably gonna be lots more efficient :) I wouldn't be surprised to find out that the power loss might be somewhat psychological either. Might be the feeling of the pedals pushing you in the soft parts of the stroke that in-part make you feel that connected with the pavement... either way, it feels good. Probly as good as a few hundred bucks for a bicycle can feel :)

[Edit: Oh! Forgot another thing I really like about fixed's.. Silence! Admittedly, bit of icing on the cake more than a core reason for riding.. but the complete lack of sound that comes from a fixed can be a pretty beautiful thing when riding early morning or late at night (when there's not a bunch of other noise to drown out freewheel clicking anyways)]