I am sorry that I am so far behind, but I will at least try to clear some things up about grayscale calibration and why color management is so important, or at least to the best of my understanding (which might be incorrect).
D65 is a point in the CIE colorspace that represents the correct "blend" of red, blue, and green primaries. Also, for all of these primaries (and secondaries as well) to appear correctly on the screen, they must also be on very specific targets in the CIE colorspace. I don't know the coordinates offhand, but I'm sure they can be researched rather easily. The problem here is that D65 can be reached even if the individual primaries are not properly on target. That is, If red, green, and blue were off by the right amounts, then white would still be at D65, yet the individual colors of red, blue, and green would appear incorrectly on the screen, so attaining white at D65 is NOT "good enough".
So, with a good color management system, we have the ability to move each of the primaries and secondaries on the CIE chart in order to individually calibrate these six colors - moving them along one axis affects the saturation of the color, and moving them along the other axis affects the hue of the color, so in order to get really accurate color rendition, either the six colors (3 primaries and 3 secondaries) need to be perfectly on their CIE coordinates to begin with, OR we need the ability to move them (a la color management) to their correct coordinates. Since every lamp will be different, I really think that movable primaries and secondaries are NECESSARY, not simply a nice luxury, but that's the anal part of me coming out.
Now, as Mark correctly pointed out, there is a third Z axis that you don't see when you look at the CIE chart, and that represents luminance. So, where the Pearl/Ruby's color management system fails is that it is able to control two of the axes (saturation and hue) of each of the six colors individually, but there is no way to control luminance (the third axis). If I understand Greg correctly, it seems that luminance is locked to saturation with the Sony PJs, so what ends up happening is that if you bring the color DOWN to their correct saturation points (they are oversaturated by default), then the "invisible" luminance is also brought DOWN, resulting in colors that appear on the CIE color chart as perfect, but in reality appear pale and uninvolving. The correct way to do it would be to have individual control of luminance in addition to saturation and hue on a one by one basis.
Like I said, don't take this explanation as Gospel, but I think I got it pretty much right....
IMO a good color management system is essential in order to keep a PJ correctly calibrated over the life of the lamp (and subsequent lamps), but maybe the JVC will be the exception that doesn't need this type of extensive control. My hopes are that even if such CM is not available in the user menu that there will at least be some cryptic controls in the service menu that can be used to get the job done...