I have a lot of projects using layer comps. When I convert file to Artboards in Photoshop cc2015, many things becomes chaos because layer comps now has artboard level, not only for layers anymore. As you mentioned in this post, layer comps are now to hide and show artboards by screen size, not for making states for a single screen.
I think that we need a better move here. Sometimes we need make a small changes like hovering a button or noticing an error, so layer comps is better solution than a new artboard. You will say that I can use smart objects, but smart objects is not good. It’s so hard to export all of demo screens I made and to find the right height and width of each layer in those objects to export after resizing the objects to many times in the project.
We also need a feature that automatically converting layer comps to artboards so we don’t need to select hundred layers and groups of the original files to move them to a new artboard.