[Brightcolours]

Yes, the 5DSr really only represents a 60% gain in horizontal and vertical resolution, but that can translate into smaller crops that are still print-worthy.

 

I recognize the limitations of the Canon sensors, but with the tremendous investment I have in legacy lenses, I really can't afford to switch to Nikon and I'm not yet impressed with using adapters on a Sony.

 

Anyway, as a landscape shooter, I generally don't find DR to be an issue in my choice of subject matter.

60% gain? No. From 5D mk III to 5DS® (not a follow up of the 5D mk III) a gain of 50.8% in horizontal (and of course also vertical) resolution.

The follow up of the 5D mk III will have a lower resolution sensor and will be an allround camera (higher FPS, much better video for instance). With the introduction of the 5DS® Canon already said all of this.