New code certainly carries risks that old, known code doesn't. And yes, this does carry over towards OS scheduler territory. That said, the early feedback fro

New code certainly carries risks that old, known code doesn't. And yes, this does carry over towards OS scheduler territory. That said, the early feedback from others in the React community is that the Fiber implementation is simpler overall and easier to work with than the "React Stack" implementation. Fiber is also explicitly built to support additional renderers on top of the core reconciler, while building renderers on the Stack implementation apparently required some levels of monkey-patching or reaching into internals.