I agree with you with the aesthetics of the downtube. It would look better and make more sense in a different (teardrop like) shape.
In terms of stiffness it maybe makes sense. I'm also no engineer in this area, so I'm only guessing.

Other than that, I like the design and geometrie of the frame.

For me I doesn't matter if I'll loose like 5W at 45km/h. I'm far from being a professional and I do not race.

That and other reason made me order this Frameset. I'll see how happy I am with it after it gets delivered and the build is done 

we know for a fact that rider & clothing matter more than the bike itself, it's about 80% rider and 20% bike, afaik.
That being said, a bus shaped tube is a bus shaped tube. Even without a wind tunnel, we know that tear drop / kamm tail shaped things are more aero than round things, or boxes... And we know that buses aren't aero. You wont find an aero frame with a wide, boxy shape like that, nor will you find a frame that touts its aero prowess with a boxy shape like that - until proven otherwise, ofc. Given it's an ultra light frame, and making frames of that weight at this price point is a new phenomenon, and that LC doesn't make any aero claims, i think it's safe to assume it's not aero. Whether it matters or not is subjective. But even if it "only" costs 5W at 45kmh, i try to spend my money diligently, and given how incredibly hard it is for me to raise my ftp by 5W, if i'm going to buy a frame, and if i can, i'm going to avoid buying one that screams "i'm a bus". It's a guesstimate. It's also an aesthetics consideration, as i dont find that boxy shape appealing.

You do you! i considered buying one myself for many weeks, and i'm not saying it's a bad frame, in fact i think it's a great frame! i was just detailing my thought process as i figured it could be useful to some.
Enjoy your new bike and post here about your experience and impressions!

For me that's actually what is more valuable in these forums. Analysing the different reasoning and mental model different people use to select frames/bikes/products. Question them and take my conclusions and decisions.
Thanks for sharing your inputs

I know this post is a little bit older.
Can you tell me if 20 days was the complete delivery time from China or only after arriving in Europe?

I just received my Frameset today. So far it looks good.

But I think there is one big problem. The front derailleur mount seems to small, so that the bolt from the front derailleur do not touch anything. I also can't glue the Shimano metal sticker.

Anyone have an idea what I should do now?
Did I do something wrong or is that a problem from the hanger?

The di2 Ultegra touchs the frame plate for me

The hanger is fixed by 4 screws. So if they could provide a different hanger it could work.

I'll definitely give updates when I know something new.
So far I can't go on with the build. That sucks.
If I have to go with electronic shifting, the build will be mich more expensive than planned. And I also really like mechanical shifting.