Nice technique. The number of distinct dynamic pages you expect to get hammered still must be regenerated within that second. With a longer window, some wp-admin or logged-in-user detection, and a third-party comment service, I could see this being a standard nginx wordpress configuration.
What comment systems are you thinking about? With Disqus the rest of the page shouldn't really matter at all, whether it's dynamic, cached, static etc…
Depending on one's error tolerance, maybe dynamic configuration would help (check if you're hit heavily and/or check if you're on HN/slashdot/reddit, then modify the config accordingly).
