Charlie --
There is some good stuff in the Bach mouthpiece guide:
http://www.selmer.com/products/acces.../bachmouth.pdf
And on the Schilke Loyalist page:
http://www.dallasmusic.org/schilke/H...outhpiece.html
Here is my rough'n'ready guide to the advantages of different parameters:
Rim:
Wider: better endurance
Narrower: better flexibility
Sharper: better attacks
Rounder: better endurance
Cup:
Deeper: richer sound
Shallower: less effort to play
Wider: broader sound
Narrower: less effort to play
More V-shaped: mellower sound
More cup-shaped: more focussed sound, more security
Throat/Backbore:
Larger: thicker sound, freer blowing
Smaller: less effort to play
BIG FAT "BUTS":
If you play a mouthpiece that is too big, your sound will be crappy because you will be fighting the mouthpiece.
If you play a mouthpiece that is too small, you may actually lose range because you are fighting the sound.
If you play a rim that is too round, you may hurt your endurance because the sound loses its immediacy and consequently you have to work harder to start the sound.