Just loaded some Portra 800 in 120 format in my Pentax 645 so will see how that works out.
I was using Ilford Delta 3200 and REALLY liked the results when the lights went down really low (although it blows out highlights when overexposed... or maybe it was just the way it was developed). I've tried flash and, even when bounced, I'm not too particular of the dear in headlights look.
Although, going off on a tangent here (While I await results from my low speed film) - is negative film more forgiving of flash overexposure than digital? I heard some of the Inside Analog Photo podcast interviewees saying that they were shooting -1/3 of a stop on their flash to get just a slight "kiss" of light when things got really dark. I think I tried this on digital and got underexposure...