In all the fuss about the large Deborah Voigt being replaced as Ariadne by the slenderer Anne Schwanewilms, I haven’t seen anything said about Ms. Schwanewilms except that she is thinner and not as well known. This doesn’t tell me much about her as a singer. So I’m curious: What will the Royal Opera patrons be getting for their money, other than a little black dress? There are some terrific unknown singers out there; is she one of them?