My two cents.
I found this entire thread fascinating. I have seen some quite clever Playground creations on this forum and have learned a lot from some of them, so when I saw the Thermal Regulator and the Intercooler Thermal Regulator I was intrigued. Once I got past the Superhero looking guy with the puffy raincoat about to take out (or maybe be fried by) 3 space ships, and the bad sci-fi novel intro, I read the description several times and traced through the diagrams. The first one wasn't too bad but the meaning or relevance of some of the calculated values was fuzzy to me. He lost me on the second one. Hats off to Remayz and cptninc who both seemed to understand what this thing was doing and even predict it's behavior in a smaller loop. And credit to Teknophage for thinking out of the box, and dedicating a huge amount of time to thinking about the subject in general. He also did make an earnest effort to respond to every counter statement.
Remayz's statement that Δt between coolant and ambient is the single most important metric to define rad efficiency and control fan speed is absolutely true. Ironically, coolant temp and ambient temp are the only 2 inputs to the Intercooler Regulator. I may never understand the number processing he does on these 2 values, but it would be easy to hold ambient steady and plot the output as coolant temp increases. What this does to the fan speed will depend on the curve it drives. Remayez actually did this, with less than stellar results in his case. If I understand correctly, the difference in performance was attributed to differences in the loop total thermal mass and a very flat fan curve. It surprised me that loop thermal mass apparently had such a significant effect on the behavior of the Intercooler Regulator.
Personally, I'll stick to a constant pump speed and coolant/ambient Δt for fans. If I decide to use a set-point, the PID controllers Aquasuite provides do that well. I think Taubenhaucher called it. Teknophage spent a year dinking with this and firmly believes his Intercooler Regulator is superior to simply using coolant/ambient Δt to control fan speeds. He also thinks varying pump speed is worth doing. He is pleased with how these sensors perform in his system and he will not be convinced that this an overly complex waste of time after spending a year working on it. I guess if nothing else, it demonstrates the power of AQS, misapplied or not. Certainly an interesting thread.