anyone using one of these, was thinking of getting one, what are your thoughts of this product?

I have one I'm not using it's a Kingsway Dual Sight just like those you mentioned. I tried it just didn't like the feel of it. I think my vision was the main reason I had trouble focusing and lining it all up because of my astigmatism and I don't always hunt/shoot with my glasses. If you PM me we can work out a good deal mainly just to cover shipping.