I would have it reduced by at least 50% but probably more like 75%.

It really is a personal choice. Dark ceilings are popular right now. Do you want it just a hint of the color, do you want it to stand out from the trim, do you want it to be bold but subtle?

that is not the way to go about getting a color. If the color pigment is only 25% what is the rest of it? Your color will take on tones you don't expect. The best thing to do is find another color that works with it, just like you do when you buy a blouse to go with a skirt. You are just shooting in the dark trying to find a color that way.