Curl,
Thanks for those beaut photos!

I'm interested to know the leverage ratio of your Woodward underlever.
An estimate could be made by measuring the travel of the underlever at its lower end from closed position to fully open, and then a measurement of how far the bolting has travelled between open and closed.
Those two measurments would provide an approximate lever ratio.
We could do the same measurement with a top lever system, to determine if the snap action underlever has a greater mechanical advantage over the top lever.