Thanks again for looking at this. I maybe the only one having a problem with this but hopefully my naivety can also act like fresh eyes.
So options –
Option to override and allow the command to operate in flat if selected. Users choice then they know.
Or colour, stroke or line weight is different for Sub-D and Mesh? As the commands are shared more and more there must be other examples of where a further differentiation is helpful. Just while the command is live.
Or display a ghosted version of the smooth along with the flat Sub-D that is being drawn. Clear it is not a mesh, you see the potential shape evolve as you draw and can keep the simplicity of flat to work in. Or the other way round - ghosted flat and normal smooth sub-d - as long as you can still see and snap easily to the vertices.
Right now appending in flat mode switches to smooth and leaves you guessing where the points / vertices are.