I just built up an Allez Sprint size 54 with Ultegra mechanical, except for a 105 crankset. Aluminum handlebar and stem. The weight with Look Keo pedals and basic aluminum rims / GP4K2 tires is 18.2 lbs, which is lighter than I expected. And lighter then my 2003 Fuji Gran Fondo carbon road bike.
It has me thinking about getting an extra set of 28mm wheels to run with the Allez for additional comfort and selling the Fuji.