Troubles moving from XenForo to Discourse

[pfaffman (Jay Pfaffman)]

@007

I’d like to forward existing urls and the best way to do that is going to be if IDs throughout are maintained. User IDs, Post IDs, Topic IDs, Category IDs, etc.

It is not. You need permalinks created for each user, post, topic, and category. See admin → customize → permalink. Many other importers have support for creating permalinks.