Isn't the main overheat issue with our cars "low speed driving in traffic"?
Cruising at 3000 RPM at 40 of 50 mph is moving a lot of air through the radiator. This is not where the problem that Scott is trying to address lurks.
I believe that John's test is pretty representative of the environment that can cause problems, and he gave you a very clear baseline to evaluate from.
Anyway - I would say if you don't have any cooling problems - then good for you. If you do (at low speeds, in traffic, with low airflow), John has provided solid evidence of improved cooling performance with the SACC pulley.
You decide - just think how many people do things to their car to provide a small incremental gain in horsepower. They are probably spending a lot more on modifications that provides less benefit than the SACC pulley.
PS> and OBTW - It also provides serious (some might say "amazing"?) "bling" after you install the clear plexiglass bulkhead cover bubble that SACC has in the works at their design bureau!