And I thoroughly disagree on your "conclusions"... Even with just over 4ft of water I can tell a difference in temp between the upper levels and the bottom without the main drains. With them on it is drastically different.

I would argue your assumption that since chemicals mix that temperature variances are also nil. That is far from the case.

Again, believe what you want. I have direct observation and quantifiable results to backup what I have posted. And unless you have the exact same pool setup, in the exact same environment, you have no point of reference other than flawed studies to fall back upon. I am an engineer, but far from blinded enough to think that those are the only answers and fully realize there are environmental factors that change everything compared to a set of "fixed examples". Your diatribe on pump dynamics show that you understand those aspects of engineering, so why be so obtuse on this???