I bought an mr one and its still on the way to me.
For me its the mr cos of the plaque thats wrong,it says edition 2500 while there were only a 1000 made.
But like said before the only real difference is the sharpness of the vocoder and the frown paint,helmet stand and plaque.
As for the price,the efx is a bit cheaper then the mr on ebay but on some forums you can get nice bargain.
I paid 450$ for my mr one shipped.
So the choise is up to you or you buy an efx for a nice price or you try youre luck on an mr with the wrong plaque size.