Here are some advantages to silicon brake fluid over conventional polyglycol brake fluids.
It is permanent, doesn't absorb moisture, doesn't boil, it prevents corrosion rather than causing it, it will not damage paint if it is spilled on the paint and it helps lubricate seals and other components in the brake system.
One thing I learned about silicone brake fluid in my experience with race cars is that it compresses more than regular brake fluid and can give your foot pedal and brake lever a different feel if switching from glycol based.
Lots of benefits over DOT 5 as opposed to DOT 3.
Nuff Said