The only thing that adjusting that setting does is give you a bit more of a smooth start. Too high and the ESC acts like it "kicks" in. Too low and the motor will chatter more at very low throttle.
I have exact the same problem, after uncountable tries I decide to recharge my LiPo pack and the problem goes away. But my MMM was set at customized voltage LiPo protection. h
Yeah, the deadband adjustment just lets you make the ESC more or less sensitive to initial trigger movements. If you have a good radio, then you can usually go quite low on the deadband. With my React, I have it set to the smallest setting and it's fine. Good to hear you've got it worked out, though.
You can probably increase the consistency of the neutral range on the throttle simply by using a stiffer spring on the trigger so it returns to neutral a little stronger. That is of course as long as the pot isn't dirty or just general component value drift...