  LISA will be able to detect gravitational waves from inspiralling massive
black hole (MBH) binaries out to redshifts z > 10. If the binary masses and
luminosity distances can be extracted from the LISA data stream, this
information can be used to reveal the merger history of MBH binaries and their
host galaxies in the evolving universe. Since this parameter extraction
generally requires that LISA observe the inspiral for a significant fraction of
its yearly orbit, carrying out this program requires adequate sensitivity at
low frequencies, f < 10^{-4} Hz. Using several candidate low frequency
sensitivities, we examine LISA's potential for characterizing MBH binary
coalescences at redshifts z > 1.
