Having 2 dedicated MXM slots is very good, but it's still possible that you bugger up the ROM so hard that it can't be flashed again without shorting the EEPROM or even exchanging it. Be aware of that.
If you're interested, post your vBIOS here, I'll combine it with the Mac 680 EFI later (or tomorrow).
i once made a mistake and flashed a renamed zip file instead of the ROM, haha!
still that did'nt brick the card, reflashed it again with normal bios and all was good. or something can go even beyond this kind of accident?