I had the same issue before I did mine as a scary thing to do. Essentially you are just using the Di2 to be a button, but from the riding point of view, it is absolute game changer for me. When changing power level on the top tube, you have to think about level, find the button and double check you have done the right thing. With the power on Di2, the button is under your fingertips, you can set power both up and down with a single push and it is dead easy. You will find yourself using this more often and it increased my battery range, so so much easier to drop a power level or two when needed.