I have the aluminum Dr. Diff master Cyl hope that works ok?
Have you ( or anyone) driven a car with them on( Viper calipers)? Huge difference? I mean , sure they look trick but do they perform?
You should be good with that master cylinder.
I have not used either set up yet as I haven't got that far on my car, and I always end up selling the sets I put together, so I have not personally driven either of the ARE kits yet. What I have heard from people who have used them is the lighter weight is a big advantage and the pedal feedback is much improved The pad selection also factors in considerably when you use the car for things other than street driving. Tom Quad, a member here, uses the Wilwood set up on his street drive road racer AAR and he sings its praises as one of the best setups you can make next to sticky tires.
Also keep in mind that it isn't all about total piston area. The 1st and 2nd gen Viper calipers are all four piston design. The fixed caliper design clamps the rotor from both sides, unlike the stock floating design that only has a piston on one side. The four piston design provides more consistent clamping force over a wider area some over all force is improved and driver feedack is improved.
While the caliper change does improve braking some, it's a smal gain. It's biggest gain is in reductions to unsprung weight and driver feedback. The biggest gains in actual braking capability would come from increased rotor size. Bigger rotors impart more leverage to the braking process, which is why the move to 16 and 17 inch wheels provides a huge leap in potential performance if oufollow through with the whole package.
