Just for this reason, we didn't want our client to go back to an older version which would sooner be replaced when Microsoft released updated features for Modern sites.
To address this scenario, we made some architectural changes to our AVAMIGRATRON (migration) tool with which we figured out features similar to Classic sites in the Modern view. Since Modern view did not support hierarchical structure, we followed site to site and sub-site to site migration technique.
Let's take, for example, Classic sites have blog templates but Modern site did not have it then. So we migrated all the blog content to Modern site pages (sub-site to site).
Even before Microsoft released many of the features in the Modern view then, we re-architected our migration tool, AVAMIGRATRON to accustom all the features as in the Classic sites.
"A whole lot of multiple migration time was reduced. They did not go by IBM -> Classic -> Modern migration. Instead, our shortest path (IBM -> Modern sites) saved their time. The client has the same look and feel as it was in the IBM Connections and the entire process was completed in just 4 months and we offered 2 weeks post-migration support. "