Did notice the gpl version you say in the lastest release is different for the DSL-AX82U-AX5400, as they also messed up RGB. So was 2 newer versions done.@patsio well it comes with a bounch with security fixes.. So I would say yes and the beta cycle has been quite long. Upgrading should be quite safe.
If you notice anything wrong you can always go back. Before updating take a snapshot of the settings from the UI, so you can restore it back if needed.