Consider KEL audio
http://www.kelaudio.com/products/hm-2d/
I use the HM-2D on voice-overs and it's remarkably close to a dynamic in performance. I used it in this video http://vimeo.com/21147679. I found it impossible to use my Oktava MK-319 or my Sterling ST-55 because I live downtown near a major highway's on/off ramp. I use very little treatment in my room, just a few pieces of insulation from office cubicles up against the windows. And I have 13ft of continuous window in this room.
Just as big an issue is whether any of the recommendations will work well with your artist's voice. You might want to stick with the 57/58 suggestion if you can't at least try a few out before making a purchase.