Oh it's the way Let It Go was written I think, its odd for her, she isn't normally throaty in that way. It only works electro. They altered the vocals on Let it go. the 'go,go,go' bits are autotuned. What Money Can't buy is pure unedited vocal

I think she could sing it live in the original key, she hits all the notes live on tours

Her mid-upper range has improved drastically since late 2008 (when she didn't sing in it much). We shall see.