If you've already got 451's and a UA5, why would you want to go with 184's and a V3??
451 is much narrower than the Neumann, it's just longer.
Seems lilke if you're really going to have to stealth it you have to go with the Schoeps or the MBHO. I'd rule out the Neumann because it doesn't buy you anything you don't already have. Plus the 451 will do nicely on acoustic music.
Dirk