Life and weather got in the way of me posting this before now.
FM066-SL size 54cm, purchased from Hongfu. Frame including hanger 879g, fork with cut steerer 372g.
Hongfu seatpost cut to 280mm 105g, plus hardware 65g.
Ultegra 6700 shifters 442g, front derailleur 89g and rear derailleur 192g. Ultegra 11-28 cassette and chain.
Rotor 3Df compact crankset with BSA bottom bracket 771g.
Ultegra 6700-C carbon pedals 259g.
Prologo C.150 saddle 154g.
Planet X cnc brakes 212g including hardware and pads.
Handlebars FS Wing Pro Compact 42cm aluminium 258g.
Deda Zero1 stem 100mm 136g.
Pro-lite Bracciano wheelset 1516g including rim tape. Pro-lite alloy skewers 116g.
Continental Supersonic tubes 110g.
Continental GP4000s 25mm 460g.
Bottle cages x2 ebay carbon 38g.
Total, including minor bits and pieces and estimate of grease etc calculated at 7071g. My luggage scales show about that, but they are not precise. That includes pedals and cages, but not lights or Garmin cadence sensor or mount.
I am as light as I can go on brakes, and nearly as light as I can go on saddle. Obviously, I could save a bit with a SRAM Red or Force group set, but I don't like double-tap, so I am willing to accept a weight penalty for that (estimate 150g). Cranksets don't get much lighter for a british threaded bottom bracket. I could easily (but expensively) save about 70g on new handlebars and stem. I know I could save 250g on some chinese 38mm carbon clinchers.
I have priced up changes to get to 6450g, but that would cost $1300. Those changes include changing to Continental Supersonic 23mm tyres, which I am not keen on (even though it would save about 160g).
If I went for ultra-light tubular wheels, I could get to about 6200g, but that is not practical for me, either.