I'm currently running a Linksys WRT54G with the latest firmware. I was recently thinking about newer routers and I realized that aside from new features (usb drives, media, etc) and faster speeds (802.11g vs 802.11n) I simply wasn't sure if there was any reasonable justification for upgrading a router that is otherwise working perfectly fine.
So, is there any reason to upgrade from a WRT54G in terms of security precautions? I recently ran the UPnP vulnerability test on ShieldsUp! and my router passed the test.
Note: I found another question on Super User that was similar but it focused on bandwidth concerns. My concern here is purely for security.