Limits or ATV for Hobbyking Quadcopter control board?

I am tuning this control board, and the instructions say to set ATV for Roll and Pitch to 50. On my ER9X, is that the same thing as just mixing the weight of those two channels to 50 percent? For instance, I had to reverse the elevator channel to get it to work, and all I did was change the weight to -100. Do I now just change it to -50 to accomplish a 50 percent pitch ATV? Also, how important is it to do this in the first place? Is leaving it at 100 percent still okay?
 

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