Silicone brake fluid has two advantages of which I am aware:
1. It does not ruin your paint if you spill;
2. It does not attract moisture the way regular brake fluid does.
The first advantage is obvious to anyone who has ever spilled on their new paint job. The second advantage is not quite so obvious. However, if you do not drive your car for long periods of time, you may note that your brake cylinders or calipers begin to develop leaks around the seals. This is the result of moisture being attracted to the residue of brake fluid on the exposed portion of the cylinder bore. Once the moisture is there it begins to form rust right where the rubber seal runs against the bore surface. As soon as you begin to drive car again the leaks start. In the old days this was a common problem among the Corvette crowd. They would solve the problem by having the cylinders bored oversize and relined with a pressed in bronze or stainless steel sleeve. This was an expensive repair, needless to say. A much less expensive solution was the use of silicone brake fluid. The problem was made much more bearable because the silicone fluid did not attract moisture to the cylinder bore. However, you cannot simply drain the old fluid and replace with silicone. You must completely purge the old fluid as the two are not compatible. Silicone is best if used from the start in a fresh new system.
The only disadvantage of which I am aware is that silicone does have a lower boiling temperature. Hence, the problem with its use in high performance applications such as a GT40 might encounter. Once it reaches its boiling point, you get the squishy pedal feel. Also, if you are driving at high altitudes this could be a problem as the altitude makes the boiling point even lower. You do not want to be descending from Pikes Peak with silicone brake fliud in your system.
Because of its advantages, silicone fluid has been in many of my cars for years. They are stored for long periods of time but are not race cars (I would never use it in a race car). I have not noticed any of the "particulating" problem mentioned by others in this thread, but that is only my experience.
If you want the best of both worlds, do not use silicone brake fluid, but make sure that if your car is going to sit for long periods of time, you at least pump your brake pedal a few times every day or two. That will minimize the corrosion problem. Then all you have to worry about is avoiding the spills. Of course it wouldn't hurt to reline your cylinder bores also, but that is only if you have nothing else to do.
