Do bear in mind that because of the reduced sensitivity spectrum of the paper (usually uv/ blue / blue-green) the ISO numbers have to be taken with a grain of salt. You have to think about the sensitivity spectrum of your meter and also the output of your light source.
Anyway, I also tend to think of most papers as having ISOs around 3-5 or so. Indeed there may be reciprocity failure at play: when I shoot to paper, I am typically using a pinhole or stopping down quite a bit to overcome registry/flatness concerns, while also tending to overexpose habitually, because I want to fight contrast (probably best to push one's exposure a bit to an extremity of the tone curve if contrast is a big concern- that was my thinking as I recall it, which may or may not be correct). And finally, I know I will be developing by inspection and can snatch quickly enough to get what I want.
Ron mentions latent imaging keeping, I hadn't thought much about that. Actually I tend to develop quite a few hours or even a day after shooting, so maybe it is an issue, IDK. My finding, as I recall, was that the benefits of flashing were there many days after flashing, so I was just ignoring latent image stability. I also never put thought into this, I just played around some time back and concluded that it was cool. Now I have a big stash of old bromide paper and maybe I will play with it again.
About the expense of paper, well, I think you can buy large rolls of paper, and even panchromatic ra4 paper like the ilford rc digital stuff or hyper seagull.
Seems to me that one tremendous reason to shoot to paper is the ease of touchup... on the backside. Just with a pencil and eraser. I haven't made much use of that but it's got to be easier than touching up ordinary negs.
P.S. Maybe it is possible to hyper some fiber paper? Anybody tried? What would you do, treat it in hydrogen at 100F or so? This question probably reveals my complete ignorance of how different paper and film are at the chemical level.