This discussion makes me think about previous threads where I lamented the meaning of these benchmark numbers. Basically, it's difficult to relate them to the real-world. I couldn't find that thread, but in the past over at core4d.com, I would ask people to open the Grapes scene from the Asset Browser and just hit Render to Picture Viewer. At least it's an actual scene one might need to render and we all have access to that scene. It is not Corona, but will test the CPU and give you a render time.
For example, I just found a couple of older screen grabs of the Grapes test. 2013 Trashcan 6-core: 10 min, 3 sec. 2017 iMac Pro 18-core: 3 min, 19 sec. For my brain, I can figure out that's about a 223% increase in render speed. When I upgrade, that's what I want to see, not a meager 20%. I can use this info to guess how long a job will take to render on the new machine. That's just me.
I don't remember how the Corona benchmark works. Does it just render for a specific time and then just see how many rays it used?