Is adding users to the group www-data safe on Debian?

Question

Many PHP application do self-configuration and self-updating. This require apache to have write access to the PHP files. While chgrp'ing them all to 'www-data' appear like a good practice to avoid world writable, i also wish to allower users to create new files and edit exsiting one.

Is adding users to the group www-data safe on Debian? For example:

775 root www-data /var/www
644 john www-data /var/www/johns_php_application.php
660 john www-data /var/www/johns_php_applications_configuration_file

Thank you for your help.

Answer 1

I usually create a group called "webdev" and add my web developer user and www-data to the group and give it the appropriate permissions for the site/directory/files, etc.

Answer 2

Why not use mod_userdir?