I used delta 3200 a year or so ago at a twilight street fair, shooting with a Fuji 6x9. I rated it at EI 1000 and processed it in Pyrocat HD. I found that EI 800 would have given me a bit better shadow separation, and that I needed to extend the development by a minute or two to enhance the overall contrast. The results were impressive regardless of my errors, and I definitely would use the film again in flat, low-light conditions. My vote would be for the Delta 3200 for MF, but I would run a test roll in similar conditions before committing to a big shoot.