Hello
Just wanted to share a story. I can say that i have downgraded a MM New 3ds XL. The system was on 9.4.0-7U when it go to me. I had read tons about downgrading and had done so on 4 other old 3ds, each varying in firmware, lowest being 9.6. That being said i figured the device would be good to go after just a normal downgrade, Whew! was I wrong. It took me 3 hours to get the sysupdater to stop getting the invalid cia argument. I Have traditionally use cubic ninja for the downgrade. Well at the 3 hour mark that is when I turned to MenuHax of all things. After FTPing the micro sd to make sure any and all "._" were removed, I tried again. The 4th hour rolls by of triple checking the sysupdate with: (MD5, cia files, proper directories, and using FTPbrony to launch sysupdater). Finally after using menu hax 2 letting the system clean boot both times, exiting FTPbrony, to run the downgrade, it sorta worked. In the middle of the downgrade the device kicks back a black screen error with the "an error has occurred please power down the system....." All I could think is the worst. After waiting a bit and powering the system down, it turned back on black screened. After deleting the "/nintendo3ds/......./Exdata" folder the device came back on at system ver. 9.2.0-20U. Awesome I thought, After running the downgrade checker the device was about 11 or 12 title versions off. After running the whole process one more time using the same update files, sysupdater fixed the broken titles (besides amiibo). The device is now transferring a old 3ds RX to it's new Reinand using system transfer.
Just wanted to share a story. I can say that i have downgraded a MM New 3ds XL. The system was on 9.4.0-7U when it go to me. I had read tons about downgrading and had done so on 4 other old 3ds, each varying in firmware, lowest being 9.6. That being said i figured the device would be good to go after just a normal downgrade, Whew! was I wrong. It took me 3 hours to get the sysupdater to stop getting the invalid cia argument. I Have traditionally use cubic ninja for the downgrade. Well at the 3 hour mark that is when I turned to MenuHax of all things. After FTPing the micro sd to make sure any and all "._" were removed, I tried again. The 4th hour rolls by of triple checking the sysupdate with: (MD5, cia files, proper directories, and using FTPbrony to launch sysupdater). Finally after using menu hax 2 letting the system clean boot both times, exiting FTPbrony, to run the downgrade, it sorta worked. In the middle of the downgrade the device kicks back a black screen error with the "an error has occurred please power down the system....." All I could think is the worst. After waiting a bit and powering the system down, it turned back on black screened. After deleting the "/nintendo3ds/......./Exdata" folder the device came back on at system ver. 9.2.0-20U. Awesome I thought, After running the downgrade checker the device was about 11 or 12 title versions off. After running the whole process one more time using the same update files, sysupdater fixed the broken titles (besides amiibo). The device is now transferring a old 3ds RX to it's new Reinand using system transfer.
Or others 
