I quite often use hand held condensers for vocalists on stage and never found a particular problem with feedback...I suppose if stage wash levels were stupidly high it might become an issue but anything that doesn't leave you deaf after the first half hour should be fine.
If I were you, I'd add the Neumann KMS104 to your shortlist--it's a huge favourite of mine for a lot of vocal styles and, and many voices, I prefer it to the KSM9. I'd also have a look at (well, listen to!) the Rode S1, another mic that can really suit some voices. It's almost good enough to make me forgive them for their stupid "Sound Booth" demo videos.
That's what I do. I drink and I know things.
-Tyrion Lannister (and Bobbsy)