Hi Mitch.
Yes, i saw that there are quite a few tables invovled, therefore i stood away from doing it via sql-script.
Lucky me, i did not know that i have to copy the machinekey as well when "copying" the passwords, allthough i was wondering myself all the time what the hash for encrypting would be..... 
...yep, this makes sense.
I found the Users&Roles Manager from Effority, but there is one not so funny behaviour. I allready sent them a mail, maybe they are answering.
But maybe you've used it or even heard about it? So here is the error-description. And no, there are no entries in the eventlog.
This module should be able to export and import roles and users. I installed in "both worlds".
- Under the old one the XLM-File will be created (as far as I can see) correctly.
- But on the new side, nothing will be imported. Without any error.
I tested the import on 3 different running 5.1.4 versions and can’t get it.
When selecting the xml-file I get a window with all properties I could import, no groups, or better, only the groups will be listed which are already existing in the new portal but no users to import at all.
I'm afraid now, that this module isn't compatible to V5.
Thanks and Cheers
Kai