I appreciate I could pick up a Lexon Unno or Vero one-piece, or an Avian Falcon or spend some more for a Farspots F1, but if I wanted to put together a two piece cockpit that's light and still allows me to clip on aero bars for long-distance bike touring / racing, what would you use?

Needs to be compatible with FSA ACR internal routing (the stock ACR stem is like 250g!)

When you say you flexed them in your hands and they shattered, what exactly did you do?

I placed my hands in the position I would be on the drops and pushed my hands together. The bars flexed, then started to make that carbon creak/crack sound, then fractured along the tops pretty rapidly.

I'm not particularly strong - I didn't put them onto something / flex them over a point and put my weight through them (as you might if you were to attach them to your stem and then hit a pothole whilst riding).

Good to know. I usually stay away from anything scary light on Aliexpress. Those Odin Zeus stems are other item that I am curious but gonna give a pass.

I also bought a pair of these and they were shockingly flexy. So I flexed them in my hands and they shattered.

I have a policy with aliexpress handlebars that I will do this and if they snap out right they go back - I don't care about the morality, they sold a dangerous item.