well let me ask this..... you said 20 buttons. now is that gonna be 8 per player (at each 8way joystick) and then 4 at the 4way joystick?
also, im assuming, youd be using the 4 way for player 1, correct?
what spinner do you plan on using? what about trackball? that will change essentiall what you need to get encoder wise.
in my mind, i would have the 4way and 4 buttons, daisy chained to the same inputs as the player 1 8way and first 4 buttons. now if you had both spinner and trackball in USB form, then you simply could get the ipac 2 or keywiz and be done.
if however, you got trackball/spinner that needed to be controlled via board..... your better option may be to just go with the IPAC Ultimate I/O as it has the capability to run spinners/trackballs with no extra hardware (plus LED control). Thats what i went with. If i were to piece it together, LED controller here, and optic board there, it would of added up to more then just buying the ultimate i/o.
just my 2cents