For a helix with constant radius, the pitch is related to the slope of the constant tangent with respect to the axis:

pitch = PI * 2 * radius * slope

So as the radius of that helix decreases, with constant pitch, the slope increases.

The slope of a helicoid increases closer to the axis.

For a helicoid created from sweep of a variable pitch helix, and intercepted with a surface of revolution that has variable radii,
the SLOPE at some point on the surface helix, could possibly decrease, stay the same or increase, w.r.t. the variable pitch helix. (?)

- Brian

How could this script be modified to use slope angles instead of pitch units?

The approach I have been trying is making an arch with my desired slope progression curve, then wrapping it around a circle using the deform tool (the helix I want to make is constant radius, variable pitch). However when I show curve points of resulting helix, it isn't as accurate as I would like.