I have a suggestion which i think would help streamline the use of both the;
- [Shape editor tool] and
- [Pen tool]

I.e i noticed that holding alt whilst using the [Freehand and brush tool] that holding the <ALT> key at any time converts this tool into a straight line mode...

And it occurred to that a similar utilization of the <ALT> key for use with the [Shape editor tool] and [Pen tool] could similarly enable these two tools by switching the modes between each other on the fly.....

I.e if you were placing down nodes with the [Shape editor tool] you could hold <ALT> as a short cut to quickly insert a bezier node in with the click and drag action of the [Pen tool] (I.e on the fly mode switch)...
or conversely whilst using the [Pen tool] you could hold <ALT> as a short cut to quickly insert a "curve" node in with the single click action of the [Shape editor tool].

Personally I think this would be a nice tweak....