Fellow Jaap
My main requirements are:

1. Ability of slurp XML and build HTML from it
2. Ability of control access permissions and operation permissions on every page (yeah, Twiki can do this, but it's a pain set up permissions for every node and guess the right permissions set of every new node)
3. Have kind of a consistency check input so 'mortal' website users can comment and answer pools
4. Easy backup/restore operations
5. Easy, cascading, inheritable, website-driven look'n'feel customization

I would love to read you thinking. Maybe I can start up with less than this, provided that I can roll up my own solutions for the missing items (Twiki is a strong candidate, right now).

Thank you for your interest and help!