If you want to use displalcement at +4, you better have a good reason to do it.  It's OK on a 700 polys rock ( should result in  11200 polys), but don't try it on ecosytem rocks or high poly objects.
Also,  using a 120% accurate map for illumination baking is mad. Just try to bake anything so high. Either an OOM or total loss of patience.
Anyway, nice finding for those who were too lazy to read their manual.