Actually, Lelouch having geassed himself never really was relevant for the rest of season one and has not been shown to be relevant yet this season.
What the Mao Arc did was provide some C.C. backstory and leave us with the TWEEST that Suzaku killed Genbu. Also, Shirley got mindwiped, but no one cares about that anyways. Somehow, I feel those three episodes could have been better used for other purposes.
More than anything, the China Arc was just boring.