For sure, it all depends of the camera algorithm and the treatment it applies when producing the mono files. I don't know the OM cameras, I was more commenting on a general level, having tried this with other cameras and have experienced limitations with the b&w jpgs produced by my F100 at that time.
Everyone his/her own experience :-) in this. It's anyway always fine to try different approaches, as each have their benefit and their ratio simplicity/complexity. Sometimes, it can be better to simplify the entire process, other times it can be better to go deep and complex, even just for the sake of experimentation. That's also what's fun with current photography :-). One can take a pic just to try, treat it just to see, all this in this day and age is free. That was not the case when one had only 36 pictures at a given ISO settings.
Thanks Gary, I should try sometimes to take direct b&w from my Sigma fp and see how it works out for me, I could be surprised, one never knows beforehand :-).
Greg