Not to keep harping on this, but we really need feedback from Sean on:
What games is he looking to play? Any video games or only PS2 games?
In case Sean isn't familiar with MAME, a (mildly outdated) list of games and screenshots is available at
http://www.arcadeathome.com/shots.phtml.
The difference is Arcade games (MAME) generally has simpler controls (single joysticks, 1-3 buttons) and are designed to be more difficult and only last 3 - 20 minutes. Console games usually have more buttons (2 analog sticks, 8 analog buttons) and are designed to play for 1-2 hours, and are generally easy to play badly and difficult to master.
The only game I've seen Sean mention is Gran Turismo using an Interact V3 wheel and pedal set. This is a good game, but the controls (by PS2 standards) are pretty simplistic. There are similar games in MAME, but again, they aren't designed for you to play for hours on end, but there are also PC games like Need For Speed, which are very similar to Gran Turismo.
Final Point - and it applies to a MAME cab as well - the controller needs to be designed for the games it will be used for.
In other words, if Sean only plays games that require the left analog stick and two function buttons, we are being counter productive trying to design for both analog sticks and all ten buttons. (In that a system that only supported two buttons would be easier for him to use for those games).
Example for the rest of the board - if you are the only one in the house that likes arcade games and you play Galaga, Time Pilot, Gyruss, and Pacman - you are throwing away space and money if you build a 4-player control panel with a SF layout and spinner and trackball and trigger sticks (Frankenpanel).