I'm maintaining a module of a desktop software visualizing industrial data, imagine multiple coordinate axes, lines, custom shapes, lots of information next to the coordinate axes. Most of the stuff is interactive and performance is critical. It originates in QT3 or even QT2 and essentially uses QPainter on a QImage displayed in a raw QWidget.

Extending it becomes more and more of a burden and I was looking into refactoring it to a more modern and flexible QGraphicsView /-scene pattern, but stumbled upon posts like Should you be using QGraphicsView.

Is this warning still up-to-date?
What are reasonable alternatives when using a widget-based desktop application?