> weather users (they are race callipers, so not sealed)... I fall into both categories...
I'm not sure it's worth fretting about this. I've had my 7500 mile JW Alcons apart, and aside from an even film of brake dust around the piston top there wasn't any sign of nastiness. It's also worth considering how few aftermarket calipers have full dust seals. Those that don't: Hispec Ultralites; Caterham AP big brakes; all the small Wilwoods.
> If the Hi-Specs are available, that route sounds like a better-bet than the Pagids -
> but would I need a comp master cylinder???
If I read the Hispec catalogue right, they use 4 x 34mm pistons which is very close to the area of 2 x 48mm Triumph pistons, so no.