Switch to Dot 5 Silicone?

[92EcoDiesel Jetta]

I am tired of having to flush the brakes every year with fresh fluid. Thinking of switching to Dot 5 Silicone to lengthen the flush interval. Probably flush every 7 -8 years. Silicone is only twice the cost of Dot 3. Anyone done the switch to Dot 5