OK, here's what you really should do: practice with it right now. Just shoot a roll of the film a stop fast, develop as normal, and see what you get. We can say one thing or another out here, but you'll have to be the final judge. Take a look on the Twin Lens Life blog, about 2010 or 2011, and see what they posted about their own experiments with Portra.
Originally Posted by BradleyK