Instance Editable Variables performance

How expensive is it to mark a variable instance editable in general?
Recently I’ve been working with a team that has a lot of Unity experience, and they have this habit of creating instance editable variables. I’ve always been told it’s expensive to do this in Unreal, but I’m wondering if anyone has any concrete data to reference for this? I’m curious if it makes enough of an impact to retrain them to using class defaults in data only classes.