Interesting insight on the GR vs VMPro. I recently did a shoot out with both of these and the DMP3. I used a Neumann TLM103, NTK and V67G.
My findings:
NTK into the GR provided the most detail and smooth, almost limited quality
NTK into the VMPro was just slightly less detailed but when externally limited, can provide just as good a result with a slightly edgier sound. I think the VMPro pushed the vocal out in front a little better when you need to get over the top of the music.
There was not more than a 10% difference in the two with smoothness falling to the GR. I will buy one just for slow, ballad sounding vocals.
The DMP3 provided a less pleasing but accurate result. The transient response and slew are just not there but hey, for $189 it produces great guitar reproduction.