I have 10 acres fenced high tensile to 7' with 9 wires (every 6 inches at the bottom). i have some fluttering stuff on it so they see it. Above 3' it alternates hot and ground. I get a deer inside a couple times a year, mostly because they were scared and ran through it. Any deer that figure it out have to be culled. I never have it off for more than a few minutes. The foxes definitely dont see it as a barrier, I've seen them jump through it. We have bears and had bees, and it suited both deer and bears. It is very very hot, at least 8kV.
This way my tender orchard is not getting obliterated every two weeks. more innovative deer would probably figure it out ours are pretty tame. I could add an attachment on the top with something fluttering as well, but so far so good. They have a hard time seeing it up high, and cant judge the height. I think its almost better not giving them a good look at it. I have seen them bounce off it, it is pretty tight (about 150lbs tension).