What would be the evaluation metric? Certainly measures like "engagement" could give exactly the opposite signals - hide everything behind more clicks and you'll get a lot more clicks!

My clicks will be going away

Google did us a favor and made an awesome Golang client library specific to GitHub

https://github.com/google/go-github

Should Github ever decided to do a/b testing I hope it's done either per repo or per organisation rather than per user. The last thing I want is members of my team having different views of our work.

I had access to the design by flipping a switch under the 'feature preview' section of my profile menu. Had a little notification blob prompting me to see what was in there.