Thank you for writing this, I use it as a reference when explaining the difference STARTTLS and implicit TLS and why people should choose one over the other.

Another nice one is that implicit TLS is SNI routable (and thus much easier to route) -- this is the main reason for me, and I wish the standard had been updated to encourage more people to try 465 (or have a way to specify port in DNS records for example). Huge missed opportunity.