Quick update on my end:
I noticed in the long run, that I routed my rear brake housing a bit too short, causing a kink in the housing at the headset and bad rear brake action.
So I needed to put in new housing and therefore take apart the whole bike basically.
So I decided to finally build up the replacement frame instead just for the sake of trying it. Also, I switched the groupset from Campy 11sp Centaur to 12sp Record - sourced the parts slightly used for cheap. Mechanical rim brake stuff isn't really worth much any more in this day and age.
The build turned out very nice. The seatpost clamping area holds up. The BB did not cause me any trouble. The cups screwed right in, the cranks spin smoothly.
Headtube bearing seats were slightly less tight on this frame, but the surface was a lot nicer finished. On my first frame it looked kinda rough. On this, it seems it was finished with some kind of lacquer coating. Again, I needed to drill the rear brake cable exit hole at the top tube. I explicitly told Chris at VB to make sure it's properly sized and he promised to take care of it. But alas, I guess stuff like this is just something you need to be prepared to do with Chiner frames.
I got another one of the superlight SROAD cassettes. A 12sp 11-32 cassette made from one block of steel, weighing about 215g. They only had it in stock in rainbow colors. Wouldn't have been my favorite choice but now that it's on the bike, I quite like it. I found these one piece cassettes to transfer more noise, especially in combination with deep wheels. So if you like your drivetrain to be dead silent, they might not be the best choice.
The build turned out very nice. I really like the bike. I dropped some weight in the process. This build as pictured, including all accessories (without Wahoo, bottles and saddle bag of course) does now weigh 7.6kg for the biggest available frame size (XXL/54).
Thanks also to madmax for giving me setup tips with Record 12sp.
