Hi Involute, the history update mechanism that kicks in when you edit a curve needs all the input objects to be present in the current model in order for a result to be recalculated. The way the pipe script works is it creates a circle and uses Sweep to make the pipe, and then the circle is deleted. So that's why it won't work with history currently because it's not able to find the circle used as the profile for the sweep.

If you make a non-hollow pipe by drawing your own circle curve off to the side somewhere and using Sweep, that should then work for a history update when you edit the path curve. You can then make it hollow after you're done editing by selecting the end caps and using Construct > Offset > Shell.

- Michael