I am puzzled by his claim that the band is not just featuring singers for the sake of promotion. None of the guest vocalists make any evident impact on the songs. Why have guest spots at all if they don't add anything musically to the songs?
Cassadee's vocals really added to Backseat Serenade imo, and Jason's appearance on Outlines turned a 7/10 song into a 9/10 song. So....it's all a matter of opinion?