The only problem I've read about with silicone brake fluid is that it compresses a bit more than conventional brake fluid, thus confusing and adversely affecting ABS systems.
In my R107, I've used silicone since 1984, original seals--have NEVER flushed it--and have absolutely no problems.
In the VW, I've used it since 2000, original seals--have NEVER flushed it--and similarly, absolutely no problems.
When I get my 230SL on the road, it will also be silicone, although the 230 will have all new rubber.
Joe