One final thing though, as to the question
"How refactor-friendly is Godot really?"
Less friendly than Unity. GDScript doesn't have great refactoring support. C# and C++ are much better in that regard. Certainly with Strings, sometimes references can break, even if you're careful, and if you have a large project it can be difficult to refactor all the uses of a particular string. Personally I like to overcome this by keeping my strings in one place and then referencing those variables. For example, my Config class contains StringName variables for every InputAction I have named, and I can access those from anywhere.