It gives a pretentious impression where I live. South Africans often use French versions of ordinary names, like
Jean-Pierre (which shortens to JP, most of the time), but
Marguerite seldom gets an airing. Nobody here would pronounce it like
Margaret, but I can't answer for the USA. I far prefer
Margaret to any of its variants, but I'd only use it as a mn: the diminutives don't please me at all.