Since Onyxia is still in Ulduar content, WG tower cannons should be nerfed to match the power level of the current content. Cannons dealing 7k damage when a cloth or leather player has 20k hp is not ideal. Also Siege Engines having 85-100k HP is not ideal when in ICC content they can have up to 200k HP. This leads to an insane winrate imbalance between attackers and defenders.
Please consider my suggestion.