The vignette is ridiculous. I'm sorry, but I don't think these belong in the professional forum. Just because you photographed talent doesn't mean that you photographed them well. I think sometimes people get lost when they see photographs of "famous people", but whereas I don't value the fame of those people (I don't care for the genre of music), I can see past that and establish that they're photos of people looking off to the side of the frame.
If the vignette were to look the least bit realistic, it would be due to light falloff on the corners of the frame, but you were shooting on f/20 or so rendering the entire scene in focus. So it just looks out of place and tacky.
It's a shame you've got that full frame body and you're not putting it to good use.