From what I had seen in reviews, the Rheosmart 6 is more of a Binary on/off action when a certain temps on the CPU are reached rather than true PWM control. I could definitely be wrong however as I haven't used one...
*edit* I guess that's just one way of setting it up. It seems that it does indeed adjust the 3-pin fan speed based on PWM signal from the mobo according to the official site:
In the youtube video, it might be on and off only because of how his bios controls the PWM. The new UEFI boards often have complex fan management systems, as even the UEFI by itself can control fan RPM based on a curve, without having any software in windows.
I've always hated fan controllers because of the manual nature of them, that I don't want to think "gee, I think I'm going to play games now, so it's time to crank up the volume." That always annoyed me, so I've always hated fan controllers. Now with PWM ones, it's all automated, and as long as my fans are reasonable volume at full blast, I've got no issue with them reaching it when I'm busy focusing on gaming.