What is the status of 2.5?
At the moment there is no movement.
Is the master branch stable enough to use it instead of 2.4.24?
Micha runs the version 22.214.171.124 (or a patched version of it) in his forum. I would assume, that he as one of the developers would report problems if they would exist. So I tend to claim that version 126.96.36.199 is stable even it is not feature complete.
"Not feature complete" meant as in comparision with the planned changes. There is in example the plan to implement an upload management consisting of a few separate functions. Two of them are implemented but two or three further functions are not. So you can use what's there (in terms of: "it works") but not the whole function chain.