Since I got my VRM Box it has helped me isolate a lot of "sh*t" in my mixes.
That said... I work almost exclusively through headphones, I do not have a proper listening environment and I'm a essentially a n00b hack when it comes to mixing.*
If those things do not apply to you (as in you have a good room with good speakers and know WTF you are doing) then yes... the VRM Box probably isn't that useful aside from just some extra listening options IF you are feeling curious.
To a clowno fartwad like me? Invaluable and I'm looking forward to trying out this extra monitoring option. It all helps.
*I also don't have a car, access to all the bar PA systems I used to, can't crank up my stereo systems in my apartment, just don't have the usual mix testing options outside of my dark, silent little mixing cubby.
Edit: What I DO have is a huge bag of headphones/earbuds of varying quality that I can swap in and out so that helps a bit too.