I did some displacement tests on Emily.
I can render the image up to 1200px. When I try to render with a higher resolution 3dsmax crashes after a minute or two. I can't see any artifacts or difference when I enable/disable Adaptive.
I thought it was weird that my PC couldn't render the image larger then 1200px, so I fired up V-Ray. In V-Ray I can render the image with 12 000px just fine. But when the image size gets above 6000px, V-Ray begin to cache to the HDD. (I only have 16GB ram on this particular PC).
The problem with Corona is that it caps my RAM when calculating displacement, before the render begins. Corona is using 12GB RAM when calculating displacement, and then 6GB RAM when rendering. While V-Ray has the same 6GB RAM usage throughout the whole process.
I have uploaded some comparison pictures and CPU/RAM overview if people are interested. This is not a who is best comparison.
The V-Ray render is 0.5px displacement, and the Corona is 0.8px because it crashed on lower settings.