My accordion method specifies that pushing should be done against the right inner thigh. Hence, this is a upper left to lower right movement, from the accordionist point of view. I cannot see how this can be compatible with my wrist sliding down — once it is down, I can resume the upper left to lower right move, even if it's a little bit more awkward.
I like my method because it has very definite rules ("your thumb should not go further than the ridge of the instrument, the wrist should be snuggly strapped, so that pulling does not really create a space from your hand and the instrument, the fingers should be curved and the articulations tense but soft, the thumb should be outstreched and slide with the hand, …") but this one is an open question to me. "Becoming one with the accordion" is still far.
Thanks for your input!