Image quality results from the EOS 5Ds R have been added to the Canon EF 100-400mm f/4.5-5.6L IS II USM Lens Review.
You probably already guessed this, but the 100-400 L II is another of my favorite lenses.
B&H has the Canon EF 100-400mm f/4.5-5.6L IS II USM Lens in stock.