Ok DM, you knew I was gonna jump on this.
"Officially" Gigabyte themselves say you can use either @BIOS (the new version, not the one that came on the CD)
or FLASHSPI. I can confirm using FLASHSPI successfully and went from F2 directly to F6b without any problems whatsoever. I created a USB boot on a flash drive, moved the autoexec.bat and bios file to the flash drive, then did the F12 at bootup and chose to boot from the USB flash drive (select HDD option- which is what the bios see the flash drive as). It booted to the flash drive and automatically installed the bios update. (yes it's more complicated than @BIOS, but I'm old school when it comes to bios updating) Once you verify that the bios is updated and working fine- you can copy the main bios to the backup bios by doing an Alt-F12 when the main boot window displays.
If you don't an OS already installed, then I think it is safe to do a large bios jump vs incremental; I think the incremental is more for Windows sanity than anything else.