I dont think there will be noticeable difference between 8 and 16 for a typical user, but if you do some certain things like running vm or uses software like After effects then the ram makes a difference.
But werent those tests on that site more or less cpu intense tasks rather than ram intense? For example transcoding depends more on the cpu. When i have been using e.g. After effects it jumped straight to the 10gb ram usage and the difference between 8 and 16 is noticeable.
I think you're going to love your new computer. I was on the exact same boat as you and I do not regret it one bit! My computer is fast, efficient and a joy to use. Enjoy your new MacBook Pro!