I finally got around to upgrading this site from MovableType 2.66 to 3.11 (the latest). I wanted to upgrade just to get the latest plugins and to explore the new capabilities. Plus it gave me an excuse to back up my site which I’ve done only sporadically.
With improved handling for comments, I might turn them back on. In fact, a day after upgrading, I got my first comment spam, but it was easily deleted from my approval queue before it hit the site.