Well, the 2 piston D3 calipers
- Work properly
- Are simple to service
- Don't seize up if the day has a Y in it
- Don't squeak
- Fit on larger discs than stock
- Are reliable
- Work properly (I know I already mentioned this, but I though it was important enough to mention again)
I am pretty sure the FL S8 Brembos were a fashion item rather than a technical solution, since W12 had larger brakes with sensible 2-piston sliding calipers. The RS 8-pots aren't much better in terms of maintenance, although they are very effective. I do like the Porsche 6-pots from an engineering standpoint, but I haven't ever driven with them.
The downside of the D3 385mm setup is the sheer weight of the discs - 18Kg (40lbs) each
Thats just stupid and not good for handling so I plan to fit the 360s as they are a reasonable compromise in terms of braking performance v weight v cost. Alas they won't work with the very lightweight RS6 365mm discs, but you can't have everything.
If only the Porsche 6-pots could be made to work with the RS6 discs that would be a perfect solution. I keep holding out for a set of Q7 4m Akebonos, but they rarely come up in pairs, and never when I have any money.