Hi Jasen,
It is a beautiful plant and flower!
I don't think it is Onc. ensatum, but on this I am not absolutely positive. The photos in Orchid Wiz of ensatum show the blooms to have a much more contrasting color difference between the petals, sepals and lip. The petals are a chocolate brown and frilly, with the lip looking similar to what is in your photo; bright yellow with or without the center spot.
Also, I don't think it is floridanum either. I have one of these that blooms in early to mid summer.

I'm sorry that I can't be of too much use on the ID of this guy.