Re: Plywood supers?
If the plywood does not have a grade stamp then its tough to tell what it is.
Free or really inexpensive materials have a powerful pull for me. I'd first use up the plywood in any tops I might need, but then use it for hive bodies. Since the plywood may not last as long as solid wood, improve your odds by painting all sides, including the inside of the hive body.
I am aware that some may consider painting the inside of a hive body to be heretical advice, but since Barry does that how can one object?
Also, if you are serious about maximum life, before painting, brush a layer of Titebond on the exposed cut edges of the plywood (including the frame rests) and let it dry. If you do this, you can skip painting those edges, IMHO.
And don't forget the Titebond in assembling the hive bodies!
-- Victor Hugo -- "Common sense is in spite of, not the result of, education.”