The thermodynamic equilibrium (and therefore phase fractions, phase compositions, transformation temperatures, etc.) can be derived by the CalPhaD method, which also provides the basis for other models to describe properties such as the γ/γ′ lattice misfit. Combined with the multi-criteria optimization algorithm MultOpt this constitutes a powerful computational tool for alloy design. The accuracy of the two thermodynamic databases TCNI10 and TTNI8 and different versions of the property models for the mass density and the γ/γ′ lattice misfit are evaluated. Four alloys were derived by the MultOpt optimization based on a combination of the mentioned databases and property models while retaining the same optimization goals, constraints and selection criteria. Experimental results on various thermophysical and mechanical properties will be presented. The new mass density model is based on a linear regression of the correlation between the mean molar mass and the measured mass density of a large number of Ni-base superalloys and proves to be more accurate in describing the mass density, especially when low-density alloys are considered. For the databases, there is no clear winner: both databases describe certain properties quite accurately while failing for others.