What happens if you do not set up redirect script after migrating from a different software? Do you get penalized from google? How long before google naturally finds the new links and drops the old ones? Is there a penalty?
In my case, I have moved from ipb couple of days ago. Also, made some changes to forum structure since (deleted some forums, moved some posts around, renamed certain forums). Will the script work in this case or should I just let it be?
I think redirection is important, especially if you're a well established forum. It will affect your search ranking otherwise.
The redirection will still work even in your case. Bear in mind that the thread IDs, post IDs and forum IDs will be identical so even if you've moved posts and threads to different forums, the IDs still remain.
It's not just search engines you need to consider - it's all the hard links people have created - they *won't* be re-index or updated so adding the redirect ensures those links still point to something valid.
It's a no-brainer - you just set and forget. I'd recommend you do it, it doesn't cost you anything.
Success! Redirection setup correctly and working like a charm. I guess redirection makes sense even if the forum is small. That much time is saved and users coming from search engines don't get error pages hence it saves the frustration.
Spoke too soon. Redirection is working fine. However, now the site is inaccessible with 500 internal server error!