Thinking of nailing the white balance, would it be possible to view the spot meter values as normal RGB values (eg 128,128,128), updated once per second? This might prove useful, especially considering that the metering spot is movable.
I skimmed through the spot meter sub-menu, and the nearest match was values displayed in "HTML" RGB... but to me that format is harder to understand. :) I do realize there are other tools for checking WB as well, but if doable, this could be a simple and efficient addition.
Also, if you think it's feasible, the RGB range could perhaps be remapped from 0-255 to 0-99, in order to keep its display slightly more compact. The accuracy shouldn't suffer too much in doing so. For example, (0 , 128 , 255) would be displayed as 0,50,99.