Yes i know google exists but i can't find a simplified answer to this. My 990XA-UD3 mobo has a bios update that contains some CPU AGESA update and its a "beta" bios. http://www.gigabyte.com/products/product-page.aspx?pid=4434#bios Is it safe to flash this bios and is it worth for these AGESA code updates?
All bios are basically betas, if it has updates for your CPU then of course it's worth it. AGESA code updates are important enough to flash a mobo, since you have dual bios there's little risk.
Newer AGESA code is usually for added support of more modern (newly released) microprocessors. You can do it anyways just to ensure that you're running the most stable/fixed BIOS code available. Although if you're having 0 issues then I don't see much point in it.