Wise man say: "Computer software like fine wine ... let it age!"
IBM once released a boner update to VM/SP which caused the system to be un-bootable. And it wasn't like you could just stick a live-CD into the machine and get it started that way... if you applied that update, you were hosed.
The IBM rep called up in a panic. But the tape was still on the shelf .. along with two updates earlier than this one .. and I simply used it as a scratch-tape. We were running three service-levels back.
If you see a specific, highly-pervasive problem that must be addressed
in a particular update, then go ahead and apply that update. Otherwise don't bother. At "the bleeding edge," it pays to let someone else take the painful cuts for you.