Saw one of these in earnest recently during a session on Color (Colour?).
Never found the vectorscope to be much use outside lining up analogue gear but the 3D variant shows you the whole story, you can see the luma value as well. But wait, there's more!
In Color when you go into the Secondaries and start selecting the mask you can see where the mask is in the 'scope. So for a CK on the scope you can see the lobe that's the thing you want to 'catch' and there's the 'net' you're using to 'catch' it trapping it. Incredible.
Perhaps it's time for an update to the metering in Vegas, not just this quite usefull device but as we've now got 32bit the old 8bit scopes aren't technically correct I think, well at least not if working with 10bit RGB.
Bob.
Bob.