I understand your thinking about XM voice. I wouldn't buy it for the voice.
I've had it a month now and it's about the music, never even had a voice station on, in fact I locked those out. It's on 24/7 on the home stereo since we don't drive much. Jazz, classical, classic rock, disco heh, R&B, country, Sinatra, soul, Cinemagic, they had an old Miles Davis concert on last week and sometime in July they are doing a massive hit countdown across the 40's, 50's, 60's, 70's, 80's and 90's stations that will take more than a week. We haven't had the TV on except for news and weather since we got it. Best 10 bucks a month I've spent for entertainment.
http://www.xmradio.com/programming/full_channel_listing.jsp?sort=number