I think the latest OS from AT&T is 18.104.22.1680. So, yeah, you could upgrade. Like NJ posts, if it's not broke, don't fix it.
If you feel a powerful urge though, you could follow the directions found in this thread; Latest OS 9800 v22.214.171.12455 / 126.96.36.1997 (All Languages)
You can download the latest OS for your device from here; https://swdownloads.blackberry.com/D...E4F82F9F00E7D4
Choose 9800 and you will see a list of OS versions you can choose from.