On LCDs, there is absolutely no different in power consumption no matter what colour is being currently displayed. Brightness (using the slider) is another matter irrespective of the colour shown on the screen.
Good to know. Then I guess I'll need to do some research on what could be causing my quicker battery drain with IOS 7. I had my settings all very specific with the 6 version and they appear at first glance to be the same. I haven't used my iPhone any differently but at the end of my workday I end up with around 35% remaining instead around 55% pre IOS 7. So this is pretty concerning. I'm on travel this weekend and really hope my phone makes it through the day.