Originally Posted by crofrog
Wet sumps give up lubrication reliability in extreme conditions.
The 320mm disc is allot more likely to be damaged. The rotor is weaker side to side and lower making it more likely to get it by a rock or catch the ground in a crash... With a dual disc setup you also have redundancy in the system in the event you damage one rotor you can covert it to a single disc.
Not to mention it's not just about brake power, but about thermal efficiency over repeated stops...
Have you actually tried a single disc setup or is this all theoretical?
I can (and do) live with the additional risk that a 0.4" lower rotor brings, not an issue in real life IME.
I don't think I have ever read of a single person unbolting their second disc because it was damaged but you are free to carry a spare if you feel that's necessary, it will still weigh less since there is no second caliper.
With a 21" wheel and a TKC type tire even repeated stops are not going to overheat a single disc. And again, if you want to use it primarily on tarmac - presumable with a stickier tire - then the Motomaster caliper is very simple upgrade. Those hold up even on the race track in the heavier and more powerful 990 as some other inmates have tested.