He (J.J. Sanvert) uses "soft" Morgan silver dollars for magic--doesn't seem to have a problem with that.
The problem you seem to experiment with halves dollars in the States is something we experiment for years in Europe with playing cards: Almost all European card magicians use USPCC brands, cards that few peoples have seen (in Europe, bridge size is standard and cards have generally four index, the design is also different).
If we choose to use the best tools available we have to accept the fact the we use tools that peoples recognise (cards, coins) but who look a little different that the one they carry with them or use in their everyday life.
During my stay in Holland as exchange student, somebody tell my that Fred Kaps used old Dutch Gulden because they had the perfect size but that only old peoples remembered.
It is a choice you have to make for yourself, in my case, I think that the handling of (slightly) strange props is part of the image of the magician. Of course some peoples mentions trick cards but I don't think I will receive less remarks if I choose to use standard Belgian cards.
We have also the take account of the fact that coins and coinmagic has lost a lot of his symbolic during the 20th century: today, when you talk about money, few peoples think about coins, most think about bill, credit cards, stock options (sorry, I take that back). The miser dream still a wonderful piece of magic (choreography, sound) but has lost most of his emotional impact.
BTW: I remember reading a comment of K. Fulves (in Epilogue or Chronicles) about the fact that coin magic cannot be qualified as impromptu or using everyday objects since nobody except magician carry four halves dollars in his pocket. And it was written 25 years ago :) .