This is very interesting.
I would bow to the superior knowledge of Photo Engineer almost every day of the week...except today. I have been shooting paper negatives for about 4 months now, and have had my students shooting 4x5 paper negs as well. We are using Ilford MGIV fiber paper and have done exhaustive testing. Everything we're finding is that it needs to be rated at ISO 3. We're developing in Sprint paper developer diluted 1:18. We have not done any pre-flashing. That'll be the next step. These are being produced for contact printing if that matters.