SDF Modeler uses cardinal splines and B-splines. Every spline segment is converted into a cubic Bézier curve, and that’s what the SDF evaluation operates on. Catmull-Rom is just a special case of a cardinal spline.
That said, I don’t think my current approach is really feasible for real-time rendering. In general, computing accurate SDFs for Bézier curves fast enough is quite challenging, since you need to solve a quintic equation efficiently and with sufficient numerical accuracy.
Cheers,
Sascha