I have an idea to offer for DS 5.0 which came to me after using Carrara.
Carrara has the ability to allow the user to work on multiple Carrara scenes at one time. I was once working on a project (which can be viewed here: https://www.renderosity.com/mod/gallery/he-swept-the-city-with-a-cold-gaze-/2355740/) where I had one main scene, but I would use Carrara to work on elements of that main scene in separate sub-scenes. So, I could set up a couple of background characters, save them, then merge them into my main scene. I was also able to adjust background props and scene elements in the sub-scenes to merge into the main scene. It was a wonderfully efficient workflow.
Currently, with DAZ Studio, only one scene may be open at a time. If I want to work on a sub-element of my scene, I have to close my main scene, open up the sub-scene, save the sub-scene, open the main scene again, and then merge the sub-scene into my main scene. One way I've found to get around that is to keep the last beta-test of DS as a way to work on sub-scene elements, or to use DS 3. I find that the current method makes for simpler and less complicated scenes for me. Being able to work on sub-scene elements allowed me to add more detail and background elements. It would also be a great festure to be able to work on a different scene file while another one is rendering.
So, as a feature for DS 5, I'd like to suggest the ability to open multiple scene files at one time.