All 3 friends are now riding their bikes. All 3 are beginners as road bike users, big picture. 1 is a pro athlete, but not in bikes. 1 is an aero space engineer. 1 is an oil & gas engineer. they all managed to build the frame fine. They all seem happy.
I got them kick ass bikes and the result seems to be a non event, really, maybe it's a good thing
1 is super happy that the bike is full custom. the other 2 are just riding the bike tinkering with their position (the engineers, go figure).
so... yeah, unsure how helpful all that can be
They're all on conti gp5000 30C, 33 wide, 50 deep wheels from peter, and the R06 from Peter. Then the components and specs differ between bikes.
Also, having put 11,000km on my own chinese frame, ultimately, it's just a bike. If you buy something that fits you, that fits the riding you do, unless you're a pretty serious statistical anomaly, if you get the frame from a reputable seller (that's a big if), then you should be fine. From the dozen builds i've done, that's probably the main takeaway. I have a world champion friend on a trek emonda, it's just the wrong bike to ride on the flat with us, as we're all on aero bikes. That's not kool aid, that's physics. And a 400$ frame will get you there just as well as a 2000 one, afaik, if you choose wisely.
My current conclusion about all this is as follows: a branded bike off the shelf will cost you more and fit you less well than a custom OEM bike, IF you know what to order. My friend on the trek is on the wrong bike. One on a van rysel is on the wrong bars (and shitty gearing, and hookless zipp rims). one on an aeroad is on the wrong gearing. And changing anything on branded bikes instantly costs a fortune, when it really shouldnt.
I didn't expect that long lecture on Chinese frames

As your friends are beginners, I understand that they have no comparison to other road frames in terms of handling, stiffness, comfort etc.
I know for and against Chinese frames, currently riding on my first build - BXT 145, but I got issues with creaking BB and creak near setpost area, that is why I am looking for something new. I am interested in Cannondale Supersix looking frame, I was even supposed to vote for TanTan x69, but after fork failure in X68. I resigned and moved to CS-R06 about which Your review is first one on forum. If you could deliver a few photos of ready builds, I would be pleased to.
P.S.
It is hard for me to believe and agree with you that guy on emonda is dropped back due to frame aerodynamic