I was just thinking about a similar idea the other day because I have an ionic filter. I wonder what an ion unit the size of a 120mm can move in airflow. Maybe this technology could replace fans someday.
I can tell you from my experience that I'm running 49-50C at idle with the Zalman at full crack with my main fan off. If I turn the 305mm Katrina on Max, which starts sucking papers off the desk across the room and has Dorothy screaming for Toto, I'm still running 49-50C at idle. Big freakin' deal. You're absolutely right. Airflow schmairflow. It's all in the HSF.
The only thing that ever made any diff was when I ran a dryer conduit from my window 18000 BTU AC right into my case. Then I saw a 28C idle/42C load for the first and last time ever. I had to wear a coat and gloves to use the PC, but DAMN did it run cool. Ambient temp is absolutely critical. If you wanna work in an icebox, then your CPU will thank you.
325 CFM is way overkill.
Heat can only be removed from your system as fast as the HSF can disapate that heat away from the heat source. Air temperature will affect that disapation rate. The cooler the air is the fast the disapation will become and thats more heat that's being drawn out. So once your ariflow matches the rate of overall heat disapation no further cooling can happen. Your just blowing around alot of air for nothing and have waisted your money on all the exstra equipment it took to acheive that airflow.
I was more concerned with the noise levels (or lack thereof) than the CFM, although I know I wouldn't have a problem cooling the computer using that so long as the airflow in the case is good.