Got to this thread late, but . . .
Mark - Looking great so far - a couple of comments -
The ikari panel - I would think the player 2 buttons would be awkward for Ikari, but swapping the joysticks would be awkward for Assault. Frosty did it the way you did - AFAIK, none of these games used more than 3 buttons, perhaps you could add buttons on the outsides, but that might kill the symmetry.
Also - as much as possible, I would try to combine controls into as few panels as possible. I know I kind of pioneered (somewhat) the modular panels thing, but I also knew there will end up being times when I would play a game that the current panel supported just to avoid having to swap them over. The more you can avoid this, the better. (Then again the more sensitive you are to PROPER controls - leafs for Robotron, for example - the harder this is to achieve.)
1.) The GP-Wiz 49 works differently than a keyboard encoder (Duh!) I don't like having to map joystick buttons to MAME functions. I definitely want to use JOYTOKEY or another program suggested by RandyT at GroovyGameGear to make the buttons appear to the computer as keyboard keystrokes.
Interesting - I'm not sure that I would recommend a middle-ware program if it wasn't required. RBJoy would be the other program.
I am also getting some weird stuff in games that use a trackball. I am pretty sure this is because with joystick enabled, the games are mapped to use either the trackball or the joystick. On one game I was able to correct this by mapping the analog axis controls to MOUSE only. But, another game wouldn't register the trackball movement when I tried this, so I may have to manually configure the .ini files (or config) for those games.
I think I had a similar problem that I got around by turning off Analog joystick support, but then you probably can't use your buttons. I would E-mail RandyT and see if he has run into this or has any suggestions.
Also, you need to configure your FrontEnd with a hotkey to bring up the joystick mode selector (or wire up the hotkey to do it manually on the fly - I think I will add the hotkey button).
What you NEED to do is find a way for your frontend to parse controls.dat and launch the GP-Wiz software in the correct mode before starting the game. That will eventually happen, but I'm not the one to ask about doing it.
Donkey Kong has been frustrating, because the joystick doesn't seem to return to center well. The result is that when you try and stop Mario from moving forward with the hammer, he keeps going and the barrel rolls under the hammer and you die. This problem may resolve itself over time when the grommet is broken in better.
The general consensus seems to be that that will go away when it gets broken in.
6.) I like having ADMIN buttons on this panel as I am having to do a lot of controls configuring in the MAME menus to work.
Agreed although for me with a desktop panel I have pretty easy access to a keyboard. For a cab, I would think a wireless keyboard would be a good option.