There's a limit to how many things two hands can hit simultaneously--and I gotta think that limit is exactly two. Any more than that, and I think you're using feet, OR you're laying down multiple tracks on a recorder--where there's no real limit as to how many things get smacked simultaneously by one person.
As for independence, consider that Terry Bozzio's drum setup includes ~17 drums and over 2 dozen cymbals, with eleven pedals--no kidding. Guess he's good, too
...and, take a look at Richie Gajate-Garcia's video, Adventures in Rhythm for Congas. He plays a clave and/or jam block, a couple of cowbells, two congas AND timbales--doesn't do the bongo tho in this video.
Finally, on LP's web site they have a link to video clips of various players--you can see Rich Quinones play a setup identical to yours, using bongo to good effect, I think.
http://www.terrybozzio.com
http://www.lpmusic.com
Edited By Bongo Boy on Mar. 24 2002 at 21:42