Works, thanks for providing the alpha so quickly.
Remark: Some posts were empty (!) when fetched. Testing with the browser the posts were also empty when I hit "edit" - despite the fact they were displayed normally when just viewing the forum.
I found a solution: disabling the advanced editor in the forum's control panel for the specific user solved the problem in browser and TM. I remember the advanced editor had always been a source for posting problems in vB 3.x when I ran such a forum - so disabling it seems to be a good choice if you run into problems with vB3-based sites.
Just wanted to share for the case someone here runs into the same trap
Wurstmu