@DrProtocols, I understand what you're saying. But if you have not used 4-byte characters (e.g., iOS emojis) in your editing, then reversing the process should work. I ran into the problem earlier this week when working locally, where I have up-to-date MySQL, on a site that is hosted on MediaTemple and is running 5.1.73.
When I used WP Migrate DB Pro to migrate the database to my server, it converted the database collation to utf8mb4. In this case, I just needed to edit code and test with their current database to ensure that all was working, but I asked their tech support if this would be a problem if I were to need to migrate it back. The response was:
WP Migrate DB Pro 1.4.7 takes care of switching back to utf8 when going from MySQL 5.5.3+ to a lesser version.