I've used a matched pair of Viennas on acoustic guitar, on grand piano, and as drum overheads. I think they are amazing in all these applications. Very pleasant, clear, and accurate. I love the Vienna on vocals too, but I usually end up using my TC. I prefer the tube sound on most vocals. I do mostly rock and pop recordings, and usually run the mics through a Sytek MPX-4Aii preamp.
Greg Blaisdell
www.proaudiotoys.com