Here are the facts!
New users coming into Website Builder v8 have a 35% higher publish rate than in v7, publish 20% faster, and have a higher average Net Promoter Score (NPS).
Given all the changes to SEO, v8 sites also perform much better than v7 due to mobile-first focus, better performance and being optimized for conversion. Some design restrictions have been put in place to optimize website performance.
Download Website Builder Feature Comparisons, v7 versus v8 (700KB pdf)