but new 3ds xl came with 10.3 when i bought mine
It doesn't matter. The lowest firmware that's n3ds compatible out of the box is 8.1.0-XX. You can downgrade ANY n3ds from 11.2 to 8.1 if for some reason you want to. This is not like PSP where you're locked out of older versions via the motherboard (they had NINE revisions of the motherboard only to block downgrades/pandora)
2.1 ctrtransfer is only compatible because it was made to work that way. You have to "unbrick" the nand backup to be able to use it (iirc decrypt9 does this for you once you transfer) and it's still running o3ds firmware, since no n3ds existed back then. This is why being on 2.1 is unstable/dangerous.







