If you're going to use silicone DOT 5, you want to make 100% sure that the rubber is compatible. Otherwise, you may end up with seal failure. Also, while true that DOT 5 does not absorb water, it also floats on top of it. Any moisture that gets in the system will condense at the lowest point, usually as a "slug" in the lines. This will lead to soft/spongy pedal fell when the brakes are hot.
