My Question now: Does SQLSession reliable work with Zope 2.6 and future
releases or is this great / fantastic / best Zope product declared as dead??
    

I use it on 2.6 under fairly heavy load, and it works fine. Don't mistake "lack
of recent updates" with "dead" - there's been no bugs that required a new 
release, so I've not done so.
  
That's good to hear - I tried to switch back to SQLSession last weekend :-( but had no luck.
SQLSession initialized but then the standardsessionmanagement came between. I tried to delete the sessionfolder on the root - but that is not possible.
I tried to delete the sessionproduct in ..lib/python/Product ... - no luck - Zope is not willing to start.

Can you please give me a hint how to get it running ? Where is your SQLSession-folder placed?

Harald