I'm thinking what I really want, is a way to move a specific user's threads from one node to another node. It would be easier to sort/weed out duplicates and merge if needed .. instead of having thousands of my own messages in one node.. which would make pages and pages to sort through and find things. I know this from FAQ.. just need tweak it, to include "user_id = 1"
UPDATE xf_thread SET node_id = 'Y' WHERE node_id = 'X' AND user_id = '1'
Is there a way of mass moving a specific user's threads from one forum to another? - Yes!
Replace 'X' with the node ID of the existing forum and 'Y' with the node ID of the new forum, and '1' with user's ID/number. Note that the thread information, forum cache and search index should be rebuilt in the ACP -> Tools -> Rebuild Caches.