I have used the c-41 process B&W a few times to and personally I am not all that impressed with it. I have had it developed at 2 different labs and the consistency of the print is never the same. Generally speaking, sometimes it does come back in B&W sometimes it has this very irritating purple tinge to it. Granted I didn't use my regular lab, due to cost of developing 35mm. I recently had the lab monotone a roll of porta 160vc and was rather impressed with the prints that came back. Nice tones and no purps to be found anywhere. Here is one that I had monotoned, porta 160vc.