Is it true the old version of Portra 160VC used to be rated PGI 33 when it came out, but was later re-rated to PGI 40? If so the new improved 160VC film rated at PGI 34 may be quite the improvement and would wonder if by the old PGI ratings it would compare to films that were rated PGI 28? How is it that a 160 speed film would have the same PGI (grain size) as a 400 speed, or 160VC compared to 400UC? I find the improvements with the new films coming confusing with Kodaks PGI ratings. For example their new 400NC film is rated 40 which is the same as 400UC that is older technology. And same with new 160NC with 32 vs old tech 100UC with 31. Granted the extra exposure time on 100UC may account for the finer grain. Which brings me to ask anyone shoot 100UC at 160 speed and if so what are your results? I've read 100UC is more like a 160-200 speed film anyway. Also anyone shoot old 160VC at 100 and if so what are your results?