This branch is by its own definition "Unstable". In simplest terms, the purpose of experimental branch is for the development team to experiment with builds in a larger userbase than our internal QA.
Sometimes that results in us finding issues we cannot catch internally, sometimes that means we can verify fixes on issues with very low repro rates.
Sometimes the builds are very unstable. (As mentioned prior)

The branch exists for load/volume/stress testing. Those who go through the process of manually opting into this branch (its not super visible - by design) and dealing with whatever issues the current build on it may have, get to sometimes see content and systems not quite ready for prime time. However, that does not mean that is the branches purpose.
As the nature of the experimental branch is for the above mentioned testing methods, neither uptime, character data, nor stability is guaranteed.