Thanks for the reply, Rick.
I'm going to have to review all my artist tags a little more before I attempt the switch from string to list. I'm not sure I want to tackle the work (and risk) right now.
Honestly, the unpredictable behavior I came across yesterday has me more than a little spooked about using this at all.
I had been using your "filters" concept in library views, which you were good enough to share a few months ago, but the list in some cases was getting long, and I just thought that using an "artist rating" might be a good substitute... and it might be, even with the complication of duets and such... but I just can't live with random and incorrect entries creeping in. I'd report this as a bug but with the development focus being so video/tv oriented, I doubt if I would get a response.
Thanks again for your time!