That's what I meant. I hadn't shut it down, and pulled the power.It will persist across reboots. It is completely removing power from the wall that resets IPMI.
So I tried it.
I can report that my X9DRI-F can handle being powered fully off (no plug in wall) thus requiring the BMC to reinitialize, and these IPMI fan settings persist.
As mentioned previously, I don't doubt there are other models in which this is not the case. Supermicro has been anything but consistent when it comes to stuff like this over the years.
Right now I am chuckling to myself at my "innovative" solution towards accessing the BMC/IPMI when using the board as a workstation