[f_hugh]

All ROMS have to flash all things that are pertinent to the ROM, or they won't work. For example, it will flash contiguous blocks relevant to itself, and does not care about the blocks in excess of its own use. Since it only cares about (only knows about) the bits that are useful to it, the bits not modified are still of no consequence. As for radio only ROMs, my assumption is that the flash is divided up into regions with boundaries that are known to the developers, including space for the boot loader, main flash, and radio firmware, etc. Flashing back to a stock ROM should do nothing but give you ten or fifteen minutes less useful time while you wait.