The only time I had a completely new and dry braking system, when I rebuilt my BV8, I thought long and hard about using silicon fluid.
In the end, there were just enough stories of sticking cylinders, and spongy feel to put me off.
Maybe on a dry fill it would have been OK. but it was never adopted by manufacturers so far as I know.
I've been using dot 5.1 in my Roadster, until the last replacement, which has similar performance properties to silicon, but is conventional brake fluid.
Last time I had some 4.0 to use up so that went in.
