I wanted to jump in here and add a couple of things from my POV as someone that switched to Pro from X and wonders about the need for a child theme.
It would be nice if there was clarification on how much customization would necessitate a child theme. For those of us that are simply using Cornerstone to design pages, Customizer to change the layout/look and messing around with CSS it doesn't seem like there should be much of an impact - but it's hard to tell if core files are being altered in any way.
I understand that CSS doesn't port over when you install the child theme, but is anything else lost from using the built-in features such as Cornerstone and Customizer? If so, how do you export them? The Add On's feature that was on X is no longer on Pro.
While copying and pasting CSS is quite easy, if that's all that seriously needs to be done then there'd be no reason to use a child theme, right?
I could have started a new thread, but his questions ties in directly to mine - the fear of upgrading to a child theme after beginning design work. He just didn't clarify how much and what kind of work he did, but for those of us that spent a day or two tweaking things and thought "Damn, maybe I should use a Child Theme so I don't lose all this work!" - it'd be nice to know.
1.) If it's necessary when using built-in Pro theme features such as Cornerstone & Customizer.
2.) What needs to be exported & how.