The danger involved with using a mBIOS is exactly the same as using a vanilla BIOS, ie; the risk the flash process might go wrong. The chances of this are very small however and recovery is quick and painless. In the worst case scenario simply put a known "good" BIOS for your board on a floppy disk (doesnt even have to be bootable) and name the BIOS AMIBIOS. (or was it AMIBOOT? its one of those anyway ) after a few minutes and a coupe restarts you'll be looking at the POST screen.