To me, bumping a thread with new and pertinent information or commentary is better than starting a new thread. I bumped a couple that had been long dormant recently because I had something relevant to add to the discussion. I searched to see if we already had a thread on the topics, and lo and behold, we did.
Yep, if you start a new thread that echoes something we've already discussed, you'll invariably get a "we already have a thread on that" comment, and often a request for the mods to merge the threads.