We can measure pypy downloads, as well as activity on the github including the number of followers, stars, and forks of the project. The impact of cadCAD is that it's a major part of a toolset for an emerging field and practice necessary for engineering crypto economic systems. 

We would like to set benchmarks around usage of model primitives for system models once cadCAD Reference and cadCAD.jl are released and see which systems benefitted from using cadCAD and look at the impact of those systems.