The ladies at MMA Candy have just uploaded a pretty cool technique video on getting the Kimura from the 1/2 mount position, check it out.
I am going to go out on a limb here and say that I don't like this technique. I have always been trained, and I agree that position is more important than submission. It seems to me that you could get the kimura without rolling or stepping over the head. It also looks like you are leaving yourself in a position where you have nothing to stop your opponent from rolling if they tripod and straighten their leg out.
I'm sidelined with an injury right now, but if anyone gets a chance to try this technique I'd be curious to know how it works out.
Watch your thumbs Vanessa