I'm using Affinity Designer and Photo since it was released on Windows, and am really satisfied with both programs.
In addition to my wacom cintiq I'm using a Microsoft Windows Dial to manipulate brush sizes and other tool properties.
This works because you can create custom menu entries for the dial and attach keyboard strokes to those entries.
But ultimately I'd love to see direct integration of the dial directly into Designer and Photo like Drawboard PDF or Sketchable have,
where the Surface Dial UI includes direct Information about available bruhes, or that I could utilize the Dial to select tool colour directly.
(For reference: Windows Wheel Interactions (MSDN))
Is that something that you consider for an upcoming version of Affinity Photo / Designer?