I would buy the BS5 again. I kept my BS9000 - actually, my wife will not let me get rid of it, and I'm not sure that I want to. I've had no problems with it whatsoever. MOTS works pretty good - very good sometimes.
I upgraded from a BeoPort + Mac, as this was getting too fiddly - somewhere along the line my iTunes library got screwed up so the Beo4 navigation didn't work reliably, and I was never sure if I was going to get music when I pressed N.Music (or would have to reboot the mac and/or reset the BeoLink). I don't miss that.
I'm a mostly mac house, but use an old PC laptop + BeoPlayer to load lossless music to the BS5 (and program my Beo5)... although, I also used the Mac integration to copy ~70% of my music directly from the mac because I didn't feel like re-ripping 200 cds (I did re-rip my 50 or so very favorites, and will re-rip others if I find I'm unhappy with the audio quality of lame standard encoded mp3s - so far, I haven't found this necessary).
Stan