I have a 53cm Hakkalugi Disc that I built using quality, but reliable equipment and it's in the 16-16.5lb (bathroom scale) range ready to ride. I plan on getting a good scale soon, so hopefully I'll have a better idea of exact weight.
I'd love to see your build list. I just built up a china cx 53cm frame (FR602 - 1125g frame, 400g fork) with:
SRAM Rival shifters, derailleurs
BHS MTB162/252 hubs, 32h H Plus Son Archetype Rims, Sapim Laser with brass spokes
TRP Spyre 160/160 brakes (full length housing front/rear)
KMC X10SL chain
SRAM Force GXP crank with 46/36 FSA rings
SRAM PG1070 11-28 cassette
Ritchey 110mm stem, Biomax 42cm drop bars, cork tape
Ritchey 34.9 WCS seat post, Generic 30g seat post clamp, Generic faux leather 220g saddle
Look Quartz pedals
Clement PDX front tire, Mud2 rear tire, lightweight butyl tubes
25 gram front titanium skewer, 70g Shimano XT rear skewer (couldn't use the matching ti rear since it was cut for a 130mm hub)
This currently weighs about 8.2 kg.
Future plans include getting 42 gram/pair titanium eBay skewers, a slightly lighter seat post clamp (not a good ww value, but I want to change colors), Ashima Ai2 160mm rotors, trimming the seat post, cutting down the fork steerer a little more, and switch to latex tubes. I think that'll get me below 8 kg.
I can't really make more dramatic improvements unless I get a race-only wheelset (carbon tubular, fewer spokes, more exotic hubs), switch to a 1x10/11 setup, and get a carbon saddle. But this bike doubles as a commuter so the latter two switches don't make too much sense.
More generally the weight gains going from canti to disc are straightforward. The wheels need to be a little stronger (a few more spokes, a beefier hub). The rims are currently a problem since only notubes is making a disc-only rim. There are a lot more option for 29er MTB disc-only rims. The disc calipers weigh more than the canti brakes. The cable runs have to be longer. In the future, hydraulic levers/calipers will get lighter and there will be more disc-only road rim options. So the disc penalty is a well over a pound right now. Eventually the disc penalty will get under a pound.