Thank you! To be honest I think there is not much there because when I started 17 years ago my technical skills were much shallower, plotting a diagram to visualize/compare two models would have been quite a lot of work. But if I can be frank, at undergraduate level playing with equations of state is not expected nor a requirement. I’m happy to just say "there are others and they all have some common things". I‘d much rather the students and I spend our energy wrapping our heads around say the concept of entropy and what it allows us to do. Regardless, I appreciate your comment muchly (and shall look up CoolProp tomorrow).