Bill - The Macbeth chart patches are very precisely manufactured in terms of equal saturation of the primaries (R,G,B) as well as the secondaries (C,M,Y), plus a very neutral equally spaced gray scale. This is important when testing. What you term as "real" green, presumably in nature, varies tremendously, and has to be learned and accommodated through experience, exposure-wise, whether with respect to color film or black and white films, which vary in their specific green sensitivity.
Much green in nature also reflects a lot of red, orange, and yellow light due to other pigments being present, and not just the dominant green of chlorophyll, which often fades in autumn anyway. That fact make Fred's little spectrographic graph of a "red apple" versus a "leaf" rather unscientific in terms of meter response, and his other graphs are highly questionable too in terms of actual objectivity; but that's what one would expect from his county fair "snake oil" marketing approach.
Chan Tran - the Minolta and unmodified Pentax spotmeters read identically. The difference is that the Pentax is simpler to use and more robust out in the field. I find the manual dial much quicker and more intuitive to use than the Minolta pushbutton readout. Both these brands gave exceptionally consistent readings meter to meter, as well as excellent linearity within a realistic range. But in spectral terms, the SPD's of both are weighted on green, just like their own graphs show (not Picker's).
Otherwise, just because the LED readout per se of the Minolta is given in 10ths, it doesn't mean its actually anymore accurate than the Pentax. For all practical purposes, I found mine to be the same.