I replaced master cylinder, brake cylinders, new lines and filled with silicone fluid on my '66 21 years ago and have had absolutely no problems in 30,000 miles. I'm converting to front discs later this month, and am going to continue with the silicone.
You are dead nuts right on as far as mixing silicone with dot 3 type.....real mess. I think its a good idea to put a small label on your master saying "silicone fluid only".
'63 Impala SS 409/425 owned since '71
'64 Impala SS 327/300 factory 4sp p/s p/b air
'66 Impala 327/275 glide 2dr/hdtp
'66 Belair Wagon 283 700R4
'62 Impala 350/350 dual quad th350 2dr/hdtp
'00 Camaro SS 6sp hurst SLP