During my pre-purchase research I run into many threads of people alleging to the fact that glasses without the best optics perform poorly on a 5DsR body leading to the common belief that a 50 mpx body maximizes any lens flaw and requires only the best and recent glasses.
After 4 months of 5DsR extensive use I totally disagree with the above.
I have been looking through my last 2 years of pictures taken with 6D and 5DsR for a printing project and just figured out that obviously the best glasses help resolving the 50 mpx sensor but the improvements are even more noticeable when "average" glasses are used. In fact the outcome produced by the 24-105 f/4 L v.1, 85 1.8, 70-200 f/4 L from the 5DsR files blows the same files from the 6D out of the water. These lenses on the 5DsR are sharper and better in every regard at low iso.
I'm not looking for an answer - just giving (some of you) food for thought...