depending on the program you use and how you actually do a B/W conversion it can vary the result a heck of alot. i get that alot of people dont want to do any PP to images and prefer it to be as shot in the camera but i think you'll find that most people apply some work to their photos, even if it is a little. i don;t think its anything to be ashamed of.
we have moved to digital to allow us to have greater control and flexibility in the final image. so my vote is do whatever you can to get the best result as you shoot it, but dont be afraid to have a bit of a tinker in PP to get the best possible result.