Check out this idea:
1) Set up server details and such (subdomain like dev.yourdomain.com)
2) Click "Generate Test Environment"
3) A replica of your site is created in the test environment, where you can mess with stuff, test themes, install and hack an out-of-date plugin for your WP release, etc. etc.
The reasoning is that our sites change all the time. Keeping a test environment is really a pain and could likely be automated.