I have in mind a similar name for my [possible] daughter, Iona (aye oh na -or- ee oh na)...
I like the/your pronunciation of Ione better (but the origin doesn't work for my set).
How would you pronounce Iolanthe? If it's pronounce Yolanda, I like it, but people would get pretty frustrated being corrected on that ("why don't you spell it 'Yolanda' then?!"). :)
I-O-Lan-The or Yo-lanthe is too soft for me :/
Like you, I prefer Ione.