Yep,
Apples and oranges.
A-PAC is closer to Daveb's AKI than the GP-Wiz.
If you don't care about analog inputs, then:
GP-Wiz32 is cheaper - A LOT cheaper if you order one of the ECO versions.
GP-Wiz is seen as one directional (D-pad) plus 28 button gamepad.
A-PAC is seen as two directional (D-pads) plus 12 buttons each gamepads with each gamepad having an additional 16 shifted buttons available.
AFAIK, GP-Wiz does not support shifted buttons, but I could be overlooking this.