I'm surprised they haven't done this yet for 2.1. As great as a company's internal testers might be, there are still many bugs and issues that go by unnoticed or don't even come into effect until a large number players are there. More testers means its more likely these things will be caught. Plus it's basically free help as there are more than enough players willing to test new content.

You wouldn't even need to level a new character. Most other games allow you to copy over your character to test servers, or offer template characters for those that are too low. Of course, playing these characters will have no effect on your characters on the main servers and will likely be wiped at the end of the testing phase.