If I have a choice between a clever, practiced antagonist to plan and write my tests and an automated system that can fit common testing patterns to my code...

If I have a choice between a clever, practiced antagonist to plan and write my tests and an automated system that can fit common testing patterns to my code... I'm always going to get more robust results from the former. But yeah, if you're just working solo on basic stuff and need to protect against off-by-one errors and accidental mutations in later refactoring, it's a great tool. You'd never write duly antagonistic tests for your own code anyway.