I tried different approaches and for my needings this extension is the best I could get.
Great extension and so far, works like a charme.
Nothing I tried so far was able to do that. SP Upgrade does this and so far without any problems.
In a matter of seconds, my articles, categories, etc. were online on Joomla 2.5 - with the same IDs and without any errors.
Thumbs-Up for this Extension! :)
It's not as customizable as Google Analytics, but it has the main and essential features too, so there is no need to bug the visitors with Google Analytics anymore :).