node-type.tpl.php code snippets for fields to respect WF access rights

I use workflow_fields with filefield, and custom node-type.tpl.php files with my zen theme.

While the filefield project page recommend the use of CCK_field_permissions, I wonder if WF works too. My problem seems to be about roles, not states:

To keep it simple, there are a public and a private workflow states.
Users in a "public" role can only see nodes on a public state. Admins can see all of them.
Now assume we're seeing a node on a public state.

I wanted public users to be able to download files containing extracts (public files) only meanwhile admins could download full-versions (private files) as well.
Therefore we have private and public filefields.

In this public state, public users are given grant to only see the the public filefields... but they can also see the private ones.

Is it a consequence of theming? If yes, what should be the proper code to write? I couldn't find anything on this in the drupal.org documentation.
Should I rather use CCK_field_permissions?

Many thanks in advance,

Arsène