On the occasion of the release of the Switch PDF Review Module version 2.0, Enfocus Product Manager Andrew Bailes-Collins has published an article entitled Print Proofing in the Digital Age.
In addition to a historical review (starting in the 1940s), it describes the advantages of digital soft proofing methods. However, he also addresses potential problems with PDF print proofing such as overprinting and transparency:
Finally, there is a detailed description of the Enfocus PDF Review Module for Enfocus Switch. The PDF Review Module is an online proofing solution that automates the online proofing process. Print customers can view production PDFs in a browser window without having to install any software. It eliminates the need for manual handling of PDF proofs by sending a link via email without the need for user management. Proof checking and approval is done on any device that uses a browser: