VCenter Upgrade options for small sized vCenter deployments missing

So you've got the Migration Assistant to start and now you're half way through the migration assistant before you get this:

The ONLY option available to you is the "X-Large" deployment size. This is obviously less than ideal if you only want a small one! In my case, the issue was Postgres logs.

1. Log into the vCenter host via SSH and go to /storage/db/vpostgres/pg_log

2. Delete anything older than 30 days

  find . -mtime +30 -exec rm {} \;

That was enough to convince the Upgrade utility that I could have a smaller one :-)