I should expand on this a little...
My interest here was to see how B&W images that result from using just a single channel of pixels compares with downsizing a colour image converted into B&W.
Also in this test is to see if there is less chromatic aberration due to different wavelengths focusing at different locations on the sensor.
Finally, it gives me a good sense for how much sharpness I should be applying in LR. Before being able to look at the per-channel images, I was just guessing about how much correction to apply (if any.)
The catch is that the output from 4channels.exe does need work (brightening, etc) before it is really usable.
As an example of the difference, I've included 3 attachments. One is just the red channel from the file, one is colour (no adjustments) from LR, and one is after colour to B&W (no other adjustments) in LR. Of course the catch here is that the red channel is 1/4 of the size of the other two.