*Although I'm happy to use chemicals, my apiary is on an organic farm, and think it would be morally incorrect for me to use chemicals if I don't have to. I reckon I took a hit on the honey (maybe) but it did seem to control the varroa.
I garden on my 10 acres, just herbs, flowers and veggies for myself. So far, I've kept that organic, since chemicals wouldn't give me any advantage--I don't have pest problems, and have plenty of compost to use as fertilizer. Plants and seeds are expensive enough without buying more stuff.
My pets get regular, if high quality pet food, and get their shots regularly. I take medicine when Ineed it. All of which is to say I'm not a fanatic about these things.
I think the chemical route in bees bothers me because coming into beekeeping, some of the first things I read were that mites were beginning to become resistant. So that leaves FGMO, oxalic acid, small cell, essential oils, SBBs, and so on. And whatever comes down the pike from the chemical companies. And I'm having a darned hard time finding peer reviewed science around these issues. Experiments, yes. Experiments by scientists, yes. But not multiple, long term, verified stuff.
As for small cell and the Lusbys' impressive results, it would not surprise me if part of the success is that their colonies are mildly Africanized. Those genetic tests were done on their bees, and showed Caucasian, Carni, and AHB genes. We know AHBs are hardly affected at all by mites. That, and ten years of bees allowed to die if they couldn't cope with mites no doubt helped their success.
So I'm running my own experiments. I can afford to. I really do want this to be a sideline, but I also live in an area where "organic" is valued. While I probably can't meet organic standards because of where I live, if I can keep healthy hives with no chemical treatments, my honey may well fetch a higher price. And, like using compost rather than fertilizer, it's cheaper.