I have only used LR v3.x and do not appreciate its file management. I'm not fully immersed in it, however.
Moving files into and out of folders using the finder and/or Bridge is easy. Bridge tracks the files and as long as its cache is kept up to date, it functions well.
Moving files into and out of folders using the finder and/or LR is so different, that at first I didn't know what was wrong. Tthe files didn't show up in the import window, and the folder has to be "synchronized". This extra step, to me, is superfluous.
But, with regard to LR, I'm a noob.
I just can't take LR seriously when it comes to colour. ACR is THE fully featured professional RAW processing application . . .
The rendering engine of both programs is the same. However, it appears that LR v4 has the latest Adobe raw processing engine, with ACR to be updated later.