I might be a dope, but I've seen myself blind on this.

Can I, assign a user to one or several particuar categories (a post category) .

In my blog, I want i.e.

User Hassan .. only to be able to write articles/posts to category "Wine"

User Bob .. only to be able to write articles/posts to category "Beer"

User Christine .. only to be able to write articles/posts to category "Lifestyle" and "Decorations"

All users still have to be able to see and view eachothers articles.

Can this be done with Role Scoper ? or any other plugins?

Yes, Role Scoper can enable a user to post within a limited set of categories.

1. Give each user in question a WordPress role of Subscriber.
2. Navigate to Roles > Categories.
3. Select desired user(s).
4. Check the Post Author (or Contributor) role for desired categor(ies).
5. Click Update button.

Repeat for each set of categories.