I'd say it's safe to install. When many people experience software instability right after a system update, sometimes it's not the system update that was faulty, it was their system. Doing system-level upgrades can uncover problems that may not have manifested by themselves normally -- if you start with a slightly "broken" system, it may be completely broken after an upgrade. But, if your disk is in good health (reboot using the OS X install CD and repair the disk, then reboot into your user account and repair permissions) and then you install the update, chances are phenomenal that you'll have no problems.
With that being said, I'm on 10.3.8 on multiple machines, and experienced no problems with any printers or any system anomalies whatsoever -- but, I do keep a pretty clean and hack-free system. If you can't remember the last time you repaired your disk and permissions, it may benefit you to make sure your disk is in good health before proceeding.
Of course, a good backup of your system right now would be extra security. That way, you can simply revert to the old system (if you made your backup bootable by using Carbon Copy Cloner or something) if something goes awry.