review for v. 1.1.2 (06dec2018) on 01feb2019: Fantastic job! Have not seen the new design since I started using this extension (over a week ago).
I also have "Reddit Comment Collapser" and "Newsit: HN & Reddit" installed. No conflicts, all reddit-based extensions working fine together (fyi: do not have RES installed).
No matter how reddit is accessed, I only see the classic design.