This was quick one day project to modify a stock iCade core controller for use with the "Gridlee" MAME emulator app on an iPad (no longer available in the app store).
I really like the iCade controller, but out of the box there were two issues I knew I had to fix.
1) The stock microswitches are a little stiff, especially for Shmups! I replaced them with very quick and responsive Cherry brand switches.
2) There is no off switch. When a button is pressed the controller will wake up and pair up over bluetooth with my iPad, which was great, except that as long as the controller was paired my on-screen keyboard was disabled (not so handy if I needed to pause and respond to an email). Probably a work around for that, but I still prefer devices that I can definitively turn OFF.
Now that I've fixed those quirks, I am loving the iCade/Mame/iPad combination. With the scanlines & aperature mask options enabled in Gridlee, the display has a great retro look. DoDonPachi FTW!