Yes, many armchair experts out there on this one, asking this question is like asking how should we tackle climate change = never ending argument.
I think what you said is almost correct though, basically Emission nebulae are various shades of
magenta with a couple of
redder ones out there, reflection nebulae are some shade of
grey-blue with some
teal/
turquoise thrown in....then there is the dreaded
saturation 
.....
What are considered acceptable colours in imaging varies with
trends too, this is particularly the case in emission line narrowband imaging, we can be flock like at times....
Mission Brown will make a come back, I'm certain, if a couple of famous imagers manage to get it out there.
In the end, what is pleasing to one eye may not be so much to another....so keep'em black and white if you are scared to offer an option.
All good fun in the end
Mike