I divide all my hives at the end of the main flow into story and a half (a deep and a medium), I give one a new laying queen, and leave the other with the old queen. If one or the other is not doing so well, I re-combine in the early spring (or late fall if I can tell by then) with one that is doing well. If both are doing well, I can either add a second deep to both in the early spring and leave them as two hives or nuc one queen and re-combine. So far it has worked out very well (of course the key here is my southerly location that allows them to overwinter well in the story and a half configuration).
"The UNKNOWN, huh? That would be SNORBERT ZANGOX over in Waycross."