Roger's "singing" on ATD ruined for me what is otherwise a pretty good album, give me Dave any day and I have to disagree about his vocals on Pulse, I thought they were more than acceptable. As a side note, was it David singing on that Bizet tune from the Meltdown RoIO ? If so it was a remarkable performance for such a "horrible" singer.

As for the two of them complementing each other you are quite correct - Comfortably Numb is a good example, it never sounds quite right in the vocal department without the two of them together. That's just my opinion of course.