[voidr]

> Use it when you have a PHP 5.4+ codebase and just can't upgrade your client's infrastructure.

I personally would just avoid those kinds of clients, PHP 5.4 was released on 1 March 2012 and PHP 5.3 is only supported until 14 August 2014[1].

[1] http://en.wikipedia.org/wiki/PHP#Release_history

[endel]

Unfortunatelly the version 5.3 is used by 45.9% of all the websites who use PHP version 5.

Source: http://w3techs.com/technologies/details/pl-php/5/all