For open tunings long scale has advantages. With resonators, strictly from an aesthetic point of view, 14 frets just look wrong
To me...
The tonal differences between 12 and 14 fret resos can be noticed by guitarists who are carefully listening for tone, but not audience members.
The good news, IME (in my experience), is that single cones seem to be less sensitive to string tension. I can easily run 12s on my single, but my tricone definitely losses something when I do. And the tricone is longer scale, so you would think that would compensate a little.