I always heard the rudder/board hum was not good also.
In your original post, you mentioned rudder hum being good. Please explain. (no need to cite links)
My OP: "my blades are extremely fine and never hum (which is slow). "...meaning that humming blades are slow/bad. Tornado blades are extremely fine on the trailing edges (typically <1/16th") and do not hum.
My thought on the sail whistle is that I may be jamming up the jib slot to the point where wind is generating a vortex as it moves through or past the slot. Getting more air acceleration between main & jib is a good thing...might a vortex/swirl have a benefit?
Typically you want the slot open more in winder conditions...but knowing how much is key and maybe I've always gone too open too soon.
