I love the slow-motion feature. I am using it well, but of course the formula generates regular speed footage, i.e. 23fps if that's what the original was. Is there a formula to generate slow motion output (in one pass) that runs at 48fps, from 23/29fps source footage?

The only other way to achieve this is to run the output footage through DAIN a second time, far as I know.  Some clips have very fast-moving elements in them that are still moving fairly fast even in slomo (such as long hair), and they would benefit from 48fps.