[bts]

I think the biggest disadvantage of putting something like this in middleware, is that it's completely incompatible with stuff like memcache. The injection of this meta-tag is done after a memcache SET would have been done in the web app, and so if you have a reverse proxy in front of your webserver, for any cached page that's served, it won't include the injection. Also, the user-agent check that's being done in this plugin yields incorrect results in the presence of caching for similar reasons.