I finished my build end of October and have been able to ride the bike for two months.
I am now able to provide a feedback on the bike.

Build:
Frame with integrated handlebar/stem
Mechanical 105 12 speed (550 euros including disk rotors and bottom brackets)
Elite wheels Edge 50 mm (600 euros)
Tyres and tools including stand: 500 euros
Weight of the bike: 8.05 kg including bottle cages and pedals (250g)

I'm quite happy to have a bike under the 8kg bar, probably thanks to the carbon wheels.
It was easy to built, cable routing through the handlebar was also easy with the proper tool. The only hard part was routing the front derailleur cable through he frame cable stop.
I used to ride a 15-20 years old Gitane weighting 11kg or so so to me the Velobuild is great. I am not able to make a comparison with any modern and high end bike. The only thing I can say is that it's comfortable to ride and that it's silent, no creaking sound.

Cons:
The finish is not perfect, there are some imperfections in the paint especially around the wheels axe holes where paint is missing and there is a dent on the edge of the carbon headtube cover but it's not missing paint. I guess it's to be expected for such a low price. Overall, these aesthetic defects are barely visible.

Hello everyone,

First, thanks for the hundreds of really helpful messages about this frame 

I have received the frame. I'm having a bit of difficulty to route the shifting cable for the front derailleur. There seems to be too much of a bend in the cable to properly seat in the cable pass through bracket. I have read several times that the metallic piece needs to be modified with a dremel so that the cable end cap sit more horizontally in the grommet. I have carefully started to drill the upper part but it seems not enough to have the cable properly seated inside. I'm using regular Shimano ot-sp41 outer cable.
I'm afraid that if the cable runs too much horizontally in the grommet, the inner cable may enter in contact with the tire or in order to prevent it, the inner cable will be bent too much when tightened to the RD.

I would appreciate any information or pictures on how you managed to have a mechanical front derailleur installed and route the cable.
Thanks