If everything's working fine, by all means don't change your BIOS. However, if a new BIOS has a feature you'll use (no patch hack, Live disable, etc) or a fix for a bug that's affecting you, then I'd recommend flashing your chip with a new BIOS. There's almost no risk involved if you have a chip with multiple banks and you're only flashing 1 or 2 of them at a time. There's even less risk involved if you have a Xenium, as you can boot into XOS to reflash or even use recovery mode if you eff things up badly.