I think it is better for the clashers to give them the options to upgrade the wall by (elexir, gold, or both of them at the same time by dividing the cost).
upgrading wall lvl 9+ is not cheap and i wish i can upgrade my wall by dividing the cost between gold/elexir at the same time, for example i can upgrade wall lvl 9 ( 500K elexir and 500K gold ) and make real balance between my resources.
regards;

