Mjc sent me the link to one of the most useful threads on the DAZ forums ever:
It’s for everyone who wants their PBS stuff to make sense, and it’s obviously most helpful for Iray users.
Now, if there are people out there wondering why Iray and LuxRender have ‘built-in’ tonemappers, but 3Delight sorta kinda has none, well… First of all, most professional 3Delight users see their renders come to life not in the DS render window but in the i-display utility which actually has exposure controls (check out the “Edit” menu) and of course colour profiles. Moreover: with 3Delight being aimed at the movie industry, its output will generally be composited with live footage, which means that the most important thing is to get quality linear images out of it, and get them fast; then they will be tonemapped and colour-graded by the compositors to match the artistic intent of the movie mastermind. This is undoubtedly a very simplified picture of the process, but you get the drift. On the other hand, Iray and LuxRender appear to be primarily aimed at archviz – where you only need the most realistic final image of something that exists or will exist in our life; an image that will stand on its own. It makes sense to put the most controls in the rendering software, then.