FreeBSD_9.0_Port_Upgrade

[Prabhpal S. Mavi]

Dear FreeBSD Friends,

i have FreeBSD 9.0 Stable Running the following roles for past four
months. Everything is functioning smooth alright. I read that system
should be upgraded frequently. i am afraid that if i upgrade something can
break.

i am planing to run it like that until FreeBSD 9.2 is out, perhaps two
years before upgrade. i am not sure if this is a good idea. i seek your
advice about the upgrade.

ROLE:   Postfix Mail Server With Virtual Users Support Using MySQL Database,
Apache Web Server, Certificate Authority (CA). Squirrelmail, Postfix
Admin, Maia MailGuard Postfix-Admin, SPF, Postgray Filter, spamassassin,
Clamav.

i want to know the advice from experts, what is best? is it really
important to update the system to new ports available. Or once i have no
issue, i should follow golden rule. don't fix if not broken. i personally
want my system to update at all time and exclude critical ports. i read
that sometimes serious problems can occur after Perl upgrade in FreeBSD.
these are the things prevent me from upgrade. i am actually working with
CentOS / Debian for past 7 years for an ISP. Just did the first setup with
FreeBSD. please advice

Prabhpal Singh