Delibes chose the B major for a reason: it's better!
Advocating a key change, simply to make Delibes's superb operatic duet easier to sing, or easier to play is simply a form of dumbing down. It is nothing to do with being a non purist, or helping an undeveloped vocalist.
Only music teachers who are unable to sing, teach or accompany in the original key, make the kind of lame excuse as mentioned above. Lowering the key, not only affects the dramatic expression and meaning of the piece, but also undermines the composer's original intention.
The original high register was chosen by Delibes to showcase the American soprano, Marie van Zandt, and to convey the exoticism of the Orient. Those who have had the opportunity to visit India, or listen to Indian music, will know that female Indian singers are famed for the high register of their singing voices. Since the opera is set in India, and Lakme and her servant, Mallika, are Indian, I would think this rather obvious to anyone who teaches this duet.
For a truly sublime performance, sung in the correct key, listen to the coloratura Mady Mesple (Lakme) and Danielle Millet. Mady Mesple sang the main role, throughout her career 145 times, and is in many people's opinion the definitive Lakme.Dana:
I disagree with your purist approach. And I'm betting Delibes would be happy that ordinary musicians are able to appreciate his music not only as listeners but as participants.