Anyone with SL SV who chooses to downgrade to S wheels and tires will get the benefit.
I really, really don't intend to disagree with you about everything, Arnis, but the Gen I Leaf has wheel wells that are too large for the 16" wheels - they suck power through aerodynamic drag as air gets pulled into those caverns. It's pretty clear that either the car was originally designed for the 17" wheels that in the end came only with the SL until 2015 (?), or Nissan just didn't care about the extra drag, which would be stupid but not inconsistent with their overall philosophy of "Just let the salespeople promise anything and everything." I'm not sure about the 2018+ Leaf, but since the 17" wheels and tires fit, I'd guess that they too provide less drag. Now 16" wheels with LRR tires vs 17" wheels with much higher resistance tires, THAT might well give you an improvement overall - especially at lower speeds.
It is not possible to notice 7mm radius difference even looking vehicles side by side. It is exactly the same amount of diameter change that winter tires go through their lifetime
(new tire is around 8mm higher, aka 16mm diameter difference).Therefore
17" Leaf with worn winter set has tires smaller than 16" Leaf with new tires.
Drag area is what changes if vehicle has narrower tires. BMW i3 has exceptionally narrow tires for exactly that reason - better drag parameters. Though it has massive wheel wells (turning radius is awesome).