I just had a roll of BW400CN pinholl done with a push-on 'cloud filter', either first or 2nd degree of yellow, and ran the film thru a 1-hour lab. They said 'they all came out fine'. I have them scanned right to CD in stead of prints so there's a degree of 'enlargement' for on-monitor viewing. I though tthe contrast was horrible. They looked fine with a 25 unit (%?) increase in contrast on Photoshop, but I was rather surprised how flat they looked.
I had been told this film would act just like regular b/w, but I think the comments of the group here suggest they have actually done it! I'm not sure the person who told me 'just like' ever tried it.
Murray