I talked to Brad about changing the icon before, and he likes the current one. Since he's the one doing the bulk of the work on MacMAME, I think it's up to him to decide what's used. If he decides he'd like something else, I have no problem with that. An icon's an icon, and as long as it readily identifies the program it's associated with, then it's fine with me, whatever it is.
As for the whole Quarter/Euro thing, because arcade games were a worldwide phenomenon, I don't think you can use any denomination specific to any one country to represent MacMAME. Although, I suppose it's possible that the icon could be coins from multiple countries... now there's a thought.
As for tokens, eons ago, I wrote an editorial
about that. Most of it still holds true, except I like tokens more now than I did back in the day. Mainly because tokens, like arcades themselves, are becoming hard-to-find artifacts of the past.