The problem is not the flash used, it is the file system. Files can be open in RAM. If the RAM image is being flushed back to the flash when power is lost and part is not copied, you have a corrupted file system. You have to be able to do some fast writes to avoid that with any system that writes to the flash even without a file system... or you don't care about corrupted data. Under Linux corrupted data can be it won't boot.