Then again, you might come up short only once. I like twin 60m 8.7 for long routes. That is as long as is practical though, in my opinion. It is difficult to communicate between belay ledges, rope drag, management on ledges, weight. The twins still get you off quickly in storms and late descents and it opens up rap lines that look impractical otherwise.
I'm with bug. Even at 60 M, communication is almost impossible sometimes with anything other than a light breeze (I solved this by buying a pair of walkie talkies). And that 100 M rope seems like it'd be a belay staion nightmare. more pieces to place, etc. etc. I can see it having it's place, like on long sport routes (Potter's new linkup comes to mind) but in general seems like it'd be a major pain in the kiester.