It would update sysnand, no idea why you are over compicating this download the 9.5.0-23 files from the ISO site and use sysUpdater or titlemanagerI am curious though. Why do you have to hold up when booting into Gateway Mode? Wouldn't it do the same without that? I mean boot into GW mode, load the cart and when it asks, do the update?
http://gbatemp.net/threads/tutorial-how-to-update-emunand-on-a-new-3ds.393701/Because I have gotten some conflicting info on how to do it. If there was a guide, then maybe I would risk going that route.
You can also use paddington adventures (lol) and puzzles and dragons mario bros edition. both are also 9.5Just curious. Code Name Steam shows a 9.4U firmware. Garfield Kart shows a 9.5U firmware.
Can any cart be used as a firmware upgrade?