It would be nice if, in addition to "polyline" and "cascading", if there were other options for the shape of the diagram connectors.  I would like to see a "spline" option that possibly follows a similar path to the "cascading" square shape, but flows with curves.   Maybe even a configuration object, instead of a string that could define the parameters of the shape.

{ 
type: "spline", 
mode: "bezier", // or "natual" or any other spline algorithm //
maxCurves: 3, // max number of inversion points in the spline //
curveRadius: 100 // size in pixels //
// any additional properties for configuring the curve, like bezier length, instead of curve radius &c. //
}