Re: Controlled Documents
I store my documents as word files typically I just make sure that only the appropriate people have write access to where they are stored on the network.

Same here, that way when a revision is required, the editor doesn't have to seek out the original file that the pdf was created from. To work with a system of "all controlled documents are pdf files" you'd end up maintaining two versions of everything, the pdf and the "source" file.
The exception, where pdf's may be seen as more appropriate is if they contain a signature graphic of the sign-off. The question then becomes whether a graphic of a signature really provides any evidence of the sign-off, as it can be so easily replicated, or the document modified while keeping the signature.