[youtalkfunny]

I've dealt tournaments with these cards. There's absolutely no downside to having them.

One of the benefits is the player who wants to move in, no longer mutters something unintelligible or makes vague hand signals. If he isn't given his all-in sign immediately, he knows that the dealer didn't hear/understand him, and he makes his position clear before the action moves past him.

The joint where I work uses these things for tourneys (we have "all-in", we don't have one that says "call"). We currently don't use them in cash games, but you don't see nearly as many all-in's in the cash games, so it's not as big a deal.