I would consider the new LCR-017 from Lightcarbon.

https://chinertown.com/index.php/topic,4309.0.html

he is looking for an "allround bike"... or did you do a bike fitting with him? ;-)

Without commenting on the YouTubers, I think the best-value frame that has evidence of aero testing in development is probably the Elilee Blize (~$1700 shipped USD including bar).

Wheels, probably Hunt’s aerodynamicist line or the Zipp 303S? I cant think of a Chinese offering that has been developed in that manner.

Bars, EXS?

If you wont miss the extra $2K, getting the SL8 is probably worth it. Easier access to spares, easier shop service if you need it. Proven performance etc. and you will get some of that back on resale if you swap bikes every couple of years.

Regarding your concerns around fitting other bars and stems. This bike uses a 1 1/2” upper bearing, so you should be able to swap it out for headsets from Deda and FSA and use systems compatible with their designs. You will lose the shaped transition spacer. Integrated bars tend to come with fit kits including their own spacers. Higher end Chinese ones like the BigRock Skyline II even include their own C ring.

RE: 3D printing. Some people release their 3d printed designs on sites like printables. I personally do not, as I don’t want to offer support for the design or deal with people printing the designs in materials that they aren’t designed for and then telling me the design doesn’t work.

Wiggle/Chain Reaction is (or was) awesome. I'd buy all my nutrition and handlebars from them. I was able to snag a spare set of Prime carbon aero handlebars from them for $100 right before they stopped shipping to the USA.

The good news is you can still find the alloy version of those bars rebranded as "Control Tech" on Amazon. A few bucks more expensive than the Prime branded version, but the ergonomics are the best in my collection of bars.
https://www.amazon.com/dp/B087M96R9V/?coliid=I1VS1T30JAMQVF&colid=39IDL28LA9NSD&psc=1&ref_=list_c_wl_lv_ov_lig_dp_it

Alternatively I also have a pair of these FSA Vision TriMax Aero alloy bars. 380mm at the hoods and 400mm in the drops. They also provide a lot reach (90mm) which I love, and they are lighter than the Prime alloy bars. Mostly they offer full internal cable routing like the Prime bars.

Vision/FSA Website
https://shop.visiontechusa.com/en/handlebars/road-triathlon/trimax-aero

Amazon
https://www.amazon.com/Full-Speed-Ahead-Bicycle-Handlebar/dp/B089WJHZCD/ref=sr_1_4?crid=3ENRN411W326W&keywords=Full+Speed+Ahead+FSA+Vision+TriMax+Aero+Bicycle+Handlebar+-&qid=1706453600&s=sporting-goods&sprefix=full+speed+ahead+fsa+vision+trimax+aero+bicycle+handlebar+-%2Csporting%2C181&sr=1-4