How secure is proc_open?

Question

symfony

The Debian Wheezy VDS is running PHP 5.6 + nginx.
For security purposes, the settings ( /etc/php5/fpm/php.ini ) have some features disabled, including proc_open.
It was necessary to use the Symfony\Component\Process component , which required the inclusion of the mentioned proc_open.
Google suggested that enabling this feature is safe in the following cases:
- if Apache is not used;
- if a separate process is used, where PHP is launched with its own ini-file providing the desired configuration.
Is it safe in reality?
What would you recommend to do in my case? [noob detected]
Thanks for the replies.