Thank you all for the interesting answers!
Interestingly enough, when I do an in-camera B&W conversion, on the spot, with the camera's software. I can do this by first converting the RAW in to a TIFF and then in to a B&W and then even tweaking it a little (contrast, colour filter, toning, even the sharpness...). Sometimes, I find that image better then when doing it, later, in LR2.
The B&W image is a little closer to what I had in mind at the moment of the shooting. But of course, tweaking on the spot takes some time. Perhaps, that might be a little step closer to what it took to shoot in the good old analogue days. After all, nothing is wrong with taking your time wile shooting, it is not a step back, I guess...
The only thing that has to be done, the 'day after', is tweaking the image a little more in detail while seeing it on the big computer screen.
Philippe