I don't know from "old cubic." But looking at the article and the evidence presented, like I said above, I'm ready to shelve the hydros and use the OP's calculator. You will understand the material better than I, but the article references foundational research you might even be able to incorporate on your own. He just did the actual tests to confirm the corrections for fermenting/fermented beer. Now I don't have to, and I suspect Dave has already tested it out himself and doesn't need me to!
To use the calculator you just have to register with their website, a Prague-based homebrew group.