The system design is not too bad but many of the fluids available
are unsuitable for climates where there is a finite humidity level
(greater than 5%).
I've been using DOT 5 silicone fluid in my clutch cylinders for about 15
years and am about to do my second maintenance in that time. I strongly
recommend it. Others have complained about brake problems related to
silicone fluid but I have not experienced any. I suspect there are other
factors that may be more to blame than the use of silicone fluid. I might
add, though, that you should disassemble both cylinders and clean them
well, make sure the rubber parts are in good shape, before putting in the
silicone fluid and also be careful not to shake it or otherwise form air
bubbles in it because they are hard to get out. The air bubbles WILL
result in a very soft pedal because the air is a lot more compressible
than the fluid.

BTW examine your cylinders carefully for pitting before reassembling.
If you have a pitted cylinder, all bets are off and frequently the pits
are too deep to clean up with a smooth surface. If you have trouble
getting a new cylinder, they can be sleeved by White Post Restorations
in White Post, Virginia.
--
George Downs Bartlesville, Oklahoma