Very interesting thread.

Never been a weight weenie, but out of curiosity I reviewed my Strava records. I ride two bikes, one a behemoth of a recumbent that weighs in at about 35 lbs, factoring all the junk I carry in the seat bag. The other bike is a carbon fiber bike that tips the scales at about 19 lbs.

I compared two rides over the same course, not really adjusting for all sorts of stuff: I descend quicker on my bent, but the ride was in the middle of winter when I try not to raise a sweat. My road bike is of course lighter, but when I rode it yesterday I was in a bit better shape and I was trying to beat a thunderstorm home.

The results: recumbent 11.9 MPH (didn't say I was fast).
The LeMond: 13 MPH.

That's with a 16 lb. difference.

Conclusion: I wouldn't sweat an ounce or two here or there.