I had skunk getting through my fence that consistently read more than 8,000 volts on my tester. A hungry predator is a determined predator.
The best predator control is to make your livestock less appealing than other sources of food. You can provide them with food, provide them with routes through your farm so that they have easy access to food, and build deterrence. You'll never win a trapping war. If you do have an aggressive predator, find a way to train him. Once he's trained, he'll train his off-spring.
I've heard a lot of good things about the Nite Guard lights. I plan on installing a couple this coming season.
I use a solar energizer called a PRS100 from Premier out of Iowa (a recommendation from Dell) for my poultry and sheep. Premier makes a lot of different types of equipment.
For a good fencing set-up, you want to look at the output in joules of the energizer. I don't see that on the Fi Shock unit. I also would stay away from the unit just based on the price and that it's continuous power AC.