Make DOpus default image viewer outside of DOpus

Given all of the wonderful yumminess in the new DOpus Image Viewer (notwithstanding some hopefully pending improvements 1, 2, 3), I would like to make DOpus the default image viewer for my system, inside and outside of DOpus.

With all of the cool changes in DOpus 12, is this still the best method?

HOW TO: Use the Opus image viewer inside or outside of Opus

That's still the recommended way(s).