If you do this and you don't allow your slot to be updated, cartridges won't work on 9.0.x. If you do this and you do allow your slot to be updated, cartridges won't work on 8.x and lower.
sorry i mystyped my message. it should have been
If my sysnand remains at 8.1.0 and i update my EMUNAND to 9.0.0 or 9.0.1, will my gamecart slot functionality be broken?