Best way to determine effectiveness would be to get some localized before and after temps. (infrared temp gun?)
Absent of that, we may be able to get some sense by comparing the altered coolant exchange flow rates/volumes using external lines and valves, to the changes in the 2016+ heads. (which probably also had some external changes) Effective or ineffectiveness of the changes aside, if you have a hot spot, diverting and altering coolant flows is what you need to do to begin to address it.
I merely skimmed it but they're also allowing time for compression testing, cooling system pressure testing, checking stored codes on overheat, stalls, (indications of abuse,) and performing some tear-down in order to inspect the backside of the engine.