I think dot 5 gets a bad rap from some people because it’s trickier to bleed. They never get all the air out which leads to a spongier pedal, and they blame that on the silicon fluid thinking it’s more compressible or something.
Silicon brake fluid retains air easier and takes longer for those air bubbles to rise up and out. To help when using it, pour it slowly out of the container into the reservoir to avoid it getting bubbly, and when pumping the brake pedal to bleed, push slowly to avoid frothing up the brake fluid like would happen if you pump the brakes vigorously.
Take your time, fully and properly bled the pedal will be as firm as when using dot 3.