Miller,
Thanks for the explanation. The greater mechanical advantage of a longer 'arm' the sear/notch works at would indeed lower specific forces on the surfaces and reduce wear.
Your take on balanced inertia of the sears is a good one IMO.
I did not know if the Lefever safety was a trigger block or sear block type. Certainly a sear block type would be a more reliable feature if properly executed. My imagination runs to including a hammer block or maybe a simple transfer bar system (ala Ruger New Model) along with either the trigger or sear block.
