What questions (and answers) do you have about how C++ changes affect prior blueprint settings?

If you’ve set up classes in C++ that you blueprint you’ve probably come across situations where you wonder: if I make <this change> in code, how will that affect my existing blueprints? Here are a few examples of things that I have wondered:

When you have many blueprints, sometimes a simple move like renaming a variable can result in much data loss due to a large number of blueprints that used the variable. What kind of situations have you encountered when making code changes, where you wondered about how that would affect existing blueprints? I’m hoping we can use each other’s experience for reference to be able to predict whether a code change would result in data loss/corruption or not. I think turning it into a wiki article at some point would be useful as well.

Here is another I’ve come across a lot:

Q: What happens if I change a variable’s default value in C++ (constructor), will blueprints automatically adapt to use the new default value?
A: If the blueprint had a custom value for that variable wrt his parent class, it will keep that value. Otherwise, it will adapt the new default value. When compiling from inside the editor, be aware that blueprints will actually keep their current value, so they do not adapt to the new default value. If you close the editor without saving those blueprints though, the next time you start the editor the blueprints will have the new value, since no custom data was stored for that variable.

I forgot to mention in my first post: if you have a question but don’t know the answer at the moment, just post it! Its probably useful and I may want to look into it anyway for my own future reference.