I didn't get a chance to put in my two cents worth before you locked the life raft thread so I had to start this new thread.
I would recommend just leaving the threads open for a number of reasons.
1. New people come to the forum and might have some new insight on the old topic.
2. Even older posters might see something in a new post on an old thread that gives him an insight and something entirely new to add to the discussion.
3. Who knows then something important might be posted (even if the ground seems well plowed.) Remember the guy at the patent office about a hundred years ago who wanted to close the patent office because everything had already been invented.
4. If something new comes up on the old topic it is better to post it on the original topic because then all of the prior discussions will be available to anyone then reading the new post with new information. If the new information is on a brand new topic it will not be obvious that there was additional information previously presented and discussed on the topic.
5. Without being on the same thread, new information posted on a new thread but on the old topic will lack the context, especially to those new to the forum. Some of the old timers might remember that there had been a prior discussion of the topic and so know to go and look for it but it seems unreasonable to me to expect new forum members to read the list of all the old threads.
6. What extra does it cost to keep the thread alive, nothing.
gl