Personally, I would be content if I could only use tri-x, d76, and ilford mgiv in the darkroom, because it reflects my m.o. in photography. While I do love the billions of choices in b&w photography, I find myself spending so much time doing flickr searches for film/dev combos trying to find just the right look. If instead I was bound to one film/dev combo that made a very "normal" negative that is very workable, I would be much happier and more efficient. I've always been afraid of focusing too much on aesthetics(color saturation or contrast and sharpness) and thus emphasizing them in my photos rather than composition. I basically only want people who view my photos to see that they are good in color/contrast, and then stop thinking about the aesthetics there, so that they can see the composition for what it is. Thus, if every one of my photos in my portfolio was taken on the same film developed by the same developer, and this combo looks pleasing(rather than possessing in-your-face sharpness, contrast, or colors) then the viewer could forget completely about the aesthetics of my photos and only focus on the composition whilst being sub-consciously pleased by the aesthetics.
Then again, darkroom work could become much less exciting with only one film/dev/paper combo, but I wouldn't mind this because, unfortunately, the processes of the black and white darkroom aren't as fun to me as they are some APUGers(whom I envy). To me, darkroom work is exactly that, work, that I perform because I want to get a final image that I believe is only obtainable through the b&w film process.