Server does not run PHP 5.3.*
So no.
PHP 5.3.* is an unstable release. PHP does releases where odd numbers are unstable and even numbers are stable. So I keep the 5.2.* branch up to date, dont touch the 5.3.* and will eventually upgrade when 5.4.* is officially released and stable.
Not to mention 5.2.* has highest level of compatibility with things. Only a few odd scripts like the latest version of moodle require 5.3.*