Yes Dave - you are on your own (unless I receive an 'imaging' invite over to your place - private jet included [non-volcanic-ash-sensitive, of course]
)
But, of course, you did ask a question that has not been answered - - - - -
When you 'hover' over the image and get the 'pixel inspector' window, the <RGB/K> values that you should see will be the 'ADU' values of the pixel at that pixel position in the image, with the following information being implied :-
You will only get all four values for a tri-channel imgae (i.e. RGB, even though the channels, as you know, need NOT actually contain the 'colours' that their name might imply)
The <K> reading is actually the 'on the fly extracted' "Luminance" information from that tri-colour image - based on a 'behind the scenes' <L> image from the L*ab extraction process
The <K> reading (if I recall correctly) is subject to the 'working colour space' restictions imposed on the image - which is why the 'colour weighting' should be set to 1:1:1
All readings are also subject to the 'pixel readout' options - and may be the 'average' (etc.) of more than just the 'single pixel' pointed to by the cursor
The readings, in 'PI Native' format, will be in the range [0.0, 1.0] - however, there are readout options available to allow you to re-scale this range to one that more closely suits your needs
So, basically, you can usually interpret 'K' in an 'RGB/K' context to be the 'extracted, or synthesised, Lum channel' associated with an RGB image, or just the value of the channel itself in a pure 'mono' image.
Does that help you? Can I come round and play?
Cheers