I think we kind of need to step back and realize we all do this for FUN.
There are some hard rules here as outlined in the rule but a lot of this is left for individual's interpretations and conscience. Conversion of color to B&W happens to be one of the hard rule and so much so that it is the first thing the screen says when you try to upload an image.
Besides, prints are reflective medium. Computer screens which scan will be "projected" is a back lit device. Images will never look exactly alike. On top of it, the latitude of film, print, and computer screens are ALL different. They can never ever be same either.
I really don't think we need to be SO critical and hard on ourselves??