Several of our "unstable" end points have now proven their value in practice, and are used by a variety of production services. While it is still possible that we want to change the return format slightly, the request interface for most of these is very simple and unlikely to change in incompatible ways any time soon.
Once T124365 is resolved and implemented we will have a policy in place that will let us to evolve response formats in incompatible ways without breaking existing clients.
As a next step, we should then promote current "unstable" entry points with stable request interfaces to "stable" status. We should also revisit existing "experimental" end points focused on the request interface stability, and consider promoting more of those to "unstable" or stable.