If I am playing a non-balanced mod game of G40, I always bring Russian mech/tanks and a couple of planes to help out China. They often can help fortify Yunnan for a critical round, or have an opportunity to blitz into Malaysia for the big bonus and additional headache. If things are not looking promising in China, the fast movers can make it back to Moscow before they are needed for a final assault on the capitol. If China has more income and Japan is hurt in the mainland of Asia, USA can spend additional income in the Atlantic. That more than compensates for the reduced units in the European theater. In fact, if the Allies can keep and fortify Yunnan, they have a very high chance of winning.