Hey Jim
I think you are underestimating Marianne. She has got a wonderful voice (and an excellent vocal technique, which is why she managed to sing even with a dreadful cold). Have you heard her last album "before the poison"? It's one of my old time favourite album, her voice is at its best on it. Granted, she did a lot of drugs in the 70s and perhaps didn't make the best decisions for herself back then but the problem has never been with her voice, her problem was the drugs. She's a true performer - she's never really dabbled with songwriting, she leaves this to others, but she can make those songs her own.