I doubt the cooling pad is that effective to be honest. The processor on these laptops isn't even on the side of the motherboard that faces down and the case doesn't make physical contact with the bottom of the laptops motherboard, there's a slight air gap.
So the heat transfer to a pad on the bottom of the laptop is extremely sub-optimal. Having a 35% larger heatsink, bigger fans providing more than 25% more airflow (which the 16" has) will likely be more effective.
I only have the 16" and a 2015 15" so I can't really compare it for you.