When I move posts I consider the following:

- if the user has less than 100 posts, they are contacted (as they may be too new to figure out how to find stuff)
- if a user is over 100 posts, I let them find it. The idea is that members have been at the forum long enough to figure out how to find their posts.

I prefer not leaving a "redirect" option since new users might mistakenly think it's ok to put posts there. In addition, this adds to additional clutter of the forums. Given the number of posts I move in a given day (anywhere from 0 - 35), it will add up.