Dekay -- I'm not sure she has that much to do with the audio problems on the CD. Both of the problems I described are strictly engineering/production issues. She should be able to sing her heart out however she wants to and the production staff ought to be able to make her sound great.
Really, I'm not sure that the sibilance on these CD's bothers me all that much (I don't have a terribly bright system), but the fact that her voice is way more dominant than the instruments is a bit annoying. I watched a concert of hers on one of the cable arts channels a few months back and was amazed at how much much more I enjoyed it over the CD's (TV fidelity issues aside). The balance between her voice and the instruments was much better and it made her sound fantastic.
Anyway, I love her voice and her music, so any imperfections in the acoustics of the CD's is easily overlooked. Still, if I could only have 2 minutes with the her engineers, I'd be a happy camper.
Cheers...Ken