Other than interface changes (and there are some, but there's a few mods at threadsdev that helps a bit), there really isn't a whole lot different feature-wise that's major. You can hide forums from those who don't have access (admin forums from general users), and there's "page views" on topics and a calendar, but not much else, Charles has done a good job of adding features to classic over the last few years.
Up to you, but if you're looking for a php/mysql solution until the next generation is out, threads will do the job well
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