So, you are rendering stills in Unreal? In your opinion, is Unreals renderengine better and/or faster than cycles? I'm not into games (yet) so I don't use Unreal. But I am looking for alternatives to cycles. Is it possible to do photorealistic renders with Unreal?
And thanks for the video, this was really interesting for me.
In my opinion Eevee(for Blender 2.8) is closer to Unreal Engine render.
The idea behind Cycles is to provide accurate results, control of the light bounces, etc.
Unreal Engine render and Eevee have been designed to provide realtime rendering, not as precise as Cycles, but still with photorealistic results.
If you are facing problems with Cycles, please take a look on Andrew Price's video that give some tips of how to speed up Cycles https://www.youtube.com/watch?v=8gSyEpt4-60
You can certainly use Unreal Engine 4 to do production renders. I currently use it for game development and this workflow is perfect for me to see what I'm going to get in engine. Once 2.8 and Eevee release, we'll have a faster workflow and will no longer need Cycles rendering in the background. It will be the exact same workflow but with Eevee's real-time rendering engine doing the heavy lifting on the Blender side. We'll have to re-evaluate whether or not UE4 should be in that production rendering pipeline but currently, it's a huge time saver for rendering and you can get AMAZING results with it.
Cycles is photorealistic.
Unreal can be made to look like Cycles.
Therefore, Unreal can be made to look photorealistic.