The double-integral form of overdamped Kramers' theory may be too
complex for analytical predictions of unfolding-force histograms.
Rather than testing the entire sawsim simulation, we will focus on
demonstrating that the Kramers' 
evaluations are working
properly. If the Bell modeled histograms check out, that gives
reasonable support for the
histogram portion
of the simulation.
Looking for analytic solutions to Kramers' , we find that there
are not many floating around in a finished form. However, we do have
analytic solutions for unforced 
for cusp-like and quartic
potentials.