My lumia 640 came with double tap to wake enabled by default. The touch settings, where thia feature is present doesnt show any warning that it would consume higher battery as my lumia 520 used to show.. Also.. The glance screen which gets automatically activated each time i put my phone out of pocket makes me feel that the screen of the phone keeps awake even during no display... So anyone here noticed significant difference in battery life keeping this featured enabled on new lumias?