[the_mitsuhiko]

That's not really the issue. The stable API is incompatible with the API that will launch with 0.16. It's not really relevant if I'm playing with incompletely API, I want to know how I can migrate to it. I did not move yet to 0.16, but I wanted to see.

The migration pain will be the same once it launches unless they revert back, which does not seem likely at all.

But the point is: potentially every API is unstable.