Ted, I think that is great. Keep on as such. Things must be right.
But...you say that you see the mites on the bees when they are thrown out of the hive. Yes, that is good that they are thrown out, but the mites that you see on the bees are probably only a tiny bit of what is actually going on in the hive. If you see the mites on bees, guaranteed there are many more mites hiding and breeding in the cells.
I don't want to sound harsh, but you should think about it, like you are, I know that. If you treated, maybe your hives would be twice as strong. The varroa sucks the hemolymph from the bees, it makes them feel weak and probably not so well. I don't know. I just know if you see mites, guaranteed there are many, many more indoors. You just don't see them. Sorry to be abrupt, but that is the way the mites work. Have a wonderful day, great life, love the life your livin'. Cindi