Hello @redgoblin ,
I am sorry that you had issues with the Migrator plugin. The plugin is PHP-based solution for site migrations, and it is susceptible to the PHP and server limits of the source hosting server. However, we would really like to take a look at the issues that you had during the migration attempts. For this, please post a support ticket through the SiteGround Helpdesk Center in your SiteGround User Area, so that we can check the case and the related server logs in details. We can then try to assist or provide more information on the issues.
Best regards,
Plamen.M
Tech Support Team
SiteGround.com