Yes I know it's all about noise, yes those 11krpm fans screech the house down, I am very familiar with them. Yes if you have a larger fan going slower you get less noise for the same spec and less power consumption. I know but 10Pa is nothing. don't be fooled by the fact that you can nearly look through a radiator, they will put up quite some pressure drop, so find the pressure you need for the flow you need and draw a line across at the pressure drop, that is your new "0" and you see how much airflow you really get.
My current setup has 5 fans, all running low speed, not too much noise but that one little 80mm fan on the CPU heatsink is a little screecher, so I am replacing it with several larger fans on a remote radiator because of the very point you make. I cannot pu 4x140mm fans on my 80mm heatsink, but I can on a radiator.