Re: John Bonham
Neil WAS a perfect time keeper, he learned how to play drums around the Test for Echo years when his instructor told him how most of drumming was done "in the air" in circles and the drum hit was at the end of a circular stroke. This was to trick him into changing his timing up a bit so he wouldn't sound so robotic.
Bonham fooled around with the time by being a bit later than expected giving you a latent sexy feel (kind of like sex), waiting in anticipation for the beat made the music exotic and alluring.
I don't think you could really have each other play the others stuff in the same stylee and patton, nor would you want to introduce someone like Stewart Copeland in that experiment either.
The results would be dissapointing in my opinion.