I've been using this design for a 3x3 piston door because I like the spiral pattern on opening and closing.
I tried using redpower to accomplish some things but I ran into issues with it. The double piston extender wouldn't function if a redpower circuit was used as an input. I ended up having to place down a vanilla repeater between the toggle latch and the input block. Although I didn't need to when I built one in my testing world. I think directionality came into play.