Fundamentally yes it was a huge shift. Practically, no, you dont need to rewrite a bunch _if_ you followed the upgrade path laid out as I described in my origin

Fundamentally yes it was a huge shift. Practically, no, you dont need to rewrite a bunch _if_ you followed the upgrade path laid out as I described in my original post. They backported a lot of stuff so that you could do the rewrite incrementally.