> I don't want to duplicate a file every time I want to do some experimentation!
But you want to keep it "in memory" while you experiment with it. The new model is more natural: if you paint on a canvas, it's painted. If you want to experiment, use the magical canvas duplicator and work on that copy, then just throw it away if you don't want to keep it.
That said, they shouldn't have brought Save As back. Imposing a new model is already upsetting, making old functionality behave differently is terrible.
But you want to keep it "in memory" while you experiment with it. The new model is more natural: if you paint on a canvas, it's painted. If you want to experiment, use the magical canvas duplicator and work on that copy, then just throw it away if you don't want to keep it.
That said, they shouldn't have brought Save As back. Imposing a new model is already upsetting, making old functionality behave differently is terrible.