Well i successfully used sysupdater and updated a 7.1 to 9.2 3ds successfully by using devmode and sysupdater, it has an option to downgrade so i do not see why it will not work from 9.9 to 9.2 by using the same pack that i used to upgrade and select the downgrade featureIt would brick your device as it is using someone else nand which are all encrypted with their own personal key that only their device has. Also attempting to downgrade with sysupdater can be dangerous as there is a possibility of user error that they miss with something that you are not supposed to which would brick your device.
















