I am late to the thread, but I have to say I think that Christine McVie and Stevie Nicks are almost completely cooked vocally. I think that is why they had Christine's mic down so low as to be non-existent (and Nicks' was almost as low in the chain). Major star mic levels are not just randomly left that low for no reason. Last year on CBS this morning in a promo for the Buckingham McVie release they did the same thing to McVie's mic - completely turned it off.
When Stevie Nicks sang Gypsy I just felt bad for her. It was way more than just 'pitchy' she has like less than 1/2 of her range and honestly sounded really bad to me. It isn't surprising though, McVie is 75 and Nicks is 70. It is sad, because both of them were distinctive vocalists who were very talented singers in their own ways. But time wins all of these battles.
Neil on the other hand literally saved the vocal performance of The Chain. I think Neil's live voice is right now much much stronger than Buckingham's live voice. I have been a fan of FM forever and seen them play that song live on literally dozens of occasions. It was a fantastic song in their set when they could really go full out vocally. But in the last few years Buckinghams live voice has been going massively downhill as well. I did like Buckingham's voice on the latest album he did with McVie. He can still record his voice and make it sound great for recordings.
In the mid 2000's both Nicks and Buckingham could still pull off a great live vocal. See the video below from 2005. It is sadly just not the case anymore. Hopefully Neil manages to keep his voice strong for another 5-10 years.
I still have the same attitude about Neil joining FM. He is so awesome, and has earned the right to do whatever crazy thing he wants to do. I just don't get it.