  Pulsars in binary systems have been very successful to test the validity of
general relativity in the strong field regime. So far, such binaries include
neutron star-white dwarf (NS-WD) and neutron star-neutron star (NS-NS) systems.
It is commonly believed that a neutron star-black hole (NS-BH) binary will be
much superior for this purpose. But in what sense is this true? Does it apply
to all possible deviations?
