Thanks for all the replies. I think I've seen other boarders use the 'endure' so maybe that is what I'll try next. I went out on the trails on sunday and had pretty well soaked my horse in the 'natural' stuff I bought. He did pretty well except then there were these BIG bugs (the BO said 'deer flies') and he would just freak when one landed on him. I understand why because one landed on my arm and just started to bite and it hurt immediately (duh, didn't think about spraying MYSELF) Between the two of us getting bombarded with flies, I just said 'screw it' and went back to the barn. He is also pasture boarded only so he is always out there. Not where the bugs are REALLY bad, but when I went to get him out of the pasture on sunday, there were regular flies all over him. So I like the 'idea' of these sprays that say they can last days - provided there is no rain and he doesn't sweat too much.
I'm on the Endure wagon. It works amazingly, stays put, doesnt gum up, and smells good, not lie citronella based sprays... Oh and it is rain and sweat proof, you have to wash the stuff off, which I like, you only have to do it every two weeks or so.