Understanding there will be a tradeoff either way, I'm wondering which of the two would be better for making internegatives from slides: 1. Using expired dedicated internegative film, reputed to be kept cold-stored since purchased. (I'm looking both at Kodak Vericolor sheet film, and Fujicolor IT-N roll film.) 2. Using fresh Portra 160 (or equivalent), using the pull method (i.e. overexpose slightly then pull during development). Thoughts?