Blender add-on: please provide an option not to modify the shader graph when changing params

Blender add-on 1.0.2: when modifying the parameter value of a Substance, the shader graph is rebuilt, for example nodes which have been disconnected are reconnected etc. Worse, when refreshing the Substance (i.e. when using a new version), the shader graph is completely rebuilt, discarding any user modifications.

Here are the modifications I am suggesting:

1) No shader graph modification on Substance parameter value change. Unless I am mistaken, there no benefit for restoring the initial graph when changing a param value. Also restoring the graph is probably taking some time that could be saved, knowing the material update on param change is quite slow, it may be be a little faster if the shader graph was not updated.

2) Regarding the sbsar update (Refresh button): provide an option in the add-on Preferences telling whether the original shader graph will be restored on Refresh. The documentation of this flag should mention that any modification to the shader graph will be lost on Refresh when this option is enabled. It would be enabled by default.

Being able to modify the shader graph is important because, as far as I know, we cannot stack materials on the same object in Blender.