I agree Epyx. I just don't like them, its easier to explain to a kid to hit the glowing red button that says EXIT to exit the game 
I've done a slow but steady 180 degree turn on this topic over the years, and now I'm 100% with Donkbaca on this one. My main cab has no admin buttons and relies on the Shift function of the IPac for Exit, Pause, Coin, TAB, etc. I'll still say that the Shift function is a Godsend, I have shifted values for not only the Mame-related admin functions (Esc, Pause, etc) but also numbers 1 - 9, Function keys F1 - F12, the letters 'Y' and 'N'... fans of C64 and other emulators will see the advantages of having the Function keys, and the ability to answer 'Y'es and 'N'o to various prompts without the need to pull out a keyboard.
HOWEVER
What I've come around to over the years is, the Cons outweigh the Pros for me. Someone mentioned "button mashers" earlier in the thread... that's where the Cons come into play. Playing a 2-player game and having to ask Player 2 to "stop pressing buttons for a second" while Player 1 presses his Start button to get back into the game, just plain sucks. But if you don't do that, you risk Player 2 hitting a random button at the same time you press the Start button (which doubles as the Shift button), and hosing up the game... a common one on my machine is, the "palette" screen will pop up. Or another common one is, Player 1 and Player 2 both hit the Start button at the same time... that's the same as hitting ESC. Game over. And if you have TWO button-mashers going at it on your machine at the same time, they're gonna screw it up, lose interest and walk away.
So for me, in the future, I will sacrifice a little authenticity of the control panel, and save myself and my guests a lot of hassle.
-EVEGames