I don’t know which Path Tracing GI method D5 use but it looks bad compared to other renderers even GPU ones like Redshift.
D5 is darker in dark areas and produce very intense GI contact shadows ( like ambient occlusion) where all other renderers have much softer more natural GI on corners :
D5 :
Redshift :
D5_Redshift.zip (3.5 MB)
It was rendered using custom settings :
Right is D5 :
It would be great if D5 Render GI looks more soften ant natural especially on corners like all other renderers which I tested ( Corona, Octane, Redshift ) - they looks near the same except D5 Render. At the moment it looks like GI + Ambient Occlusion effect.