This dataset supports the study of next-generation Compton gamma-ray sources (CGSs) based on storage rings which rely on high-power tightly focused laser beams produced using Fabry-Perot cavities (FPCs). The work re-evaluates the behavior of a two-mirror nearly concentric resonator through a newly introduced figure of merit quantifying the cavity's proximity to instability. This metric informs analysis of key design aspects including misalignment sensitivity beam coupling and beam size scaling. Data is stored in a .mat file with clearly labeled column headers matching variable names used in the publication. All plotted data is presented in the associated article. Figure 6 data was generated using elegant with the Duke storage ring lattice. Figure 10 flux data is derived from a modified version of a spreadsheet originally developed for CGS flux estimates at HIGS. All remaining data can be directly reproduced from formulas in the article.
