This plugin works particularly well with templates from Rockettheme, that use parameters in the template. No need to modify the index.php code at all. Everything can be done within the template manager.
I did run into some bumps in terms of how it works with sh404sef. It would be great if the developer could look into that at some point, since so many sites use that component. I ended up disabling sh404sef, which was kind of a bummer.
I also ran into some complications with maintaining login/sessions on the subdomain. Joomla core doesn't recognize the subdomain and therefore users don't remain logged in on the subdomains. I found the fix for that here: