Yes, this is all correct, as long as you're implicitly assuming that the CPU itself has some static power dissipation as well (which it does) in addition to the rest of the system.

Unfortunately I missed the actual benchmarks in the article that empirically measured the power difference.

I think you have it right but also my experience from optimising Android power usage was: your your intuitions are helpful for knowing what to try, but you have to test and measure everything as there are always complications. Luckily you are well equipped to benchmark it already :)