Lately I've been saying no to breathy female vocalists (I overdosed on them at CES), but because these speakers have such a clean midrange, I brought out the Ricki Lee Jones and K.D. Lang albums, with great results. The speed and clarity of the Arivas with their freedom from overhang on initial transients allow these speakers to convey spatial information extremely well. The Arivas also work exceptionally well with recordings that feature layered harmonies, separating out vocalists where you might not have been sure just how many people were on the track. On Crosby, Stills, Nash, and Young's Déjà vu [Mobile Fidelity/Atlantic], I was able to hear all four members of the group distinctly and with a clarity that had not been possible before.
Imaging was very close to what I have experienced with various planar speakers, and the Arivas did a great job reproducing spatial cues. The downside to speakers with this level of speed and resolution is that they are not forgiving of source material or components. If you are not going to use the Arivas with a complete Naim system and cables, I advise careful system matching or you will not be able to achieve their full potential. You may find yourself upgrading your system in other areas after you purchase a pair of Arivas!
My only complaint with the Arivas' performance was that they lacked a touch of dynamic range when listening at screaming-for-vengeance levels, where they tended to compress just a bit. If you don't listen to braindamage music, though, you will probably never notice this. But at high listening levels, these speakers will run out of gas.
I have enjoyed the Naim Arivas better than most speakers I have heard in this price category ($2500/pair). Just keep in mind that they require careful matching with source components to achieve the accuracy they are capable of and remember that they must be placed much closer to the wall than most other speakers. When everything lines up with the right system and a good recording, though, these speakers offer a wonderful listening experience. I wish I didn't have to box them up and send them back.