I've used the Drivekey.  In my experience, you may block updates, from ninty, as well as from the disc.  However, I've only had to go as far as 4.1.  Everything to date works fine with it.  You really should only update if you have 0-mods whether hard/soft and do not plan to do it in the future.  R.H., correct me if I'm wrong but BootMii is partially useless as an IOS correct?