I am not sure what kind of pigs you guys had but I pastured mine with electric fence and they do not charge when threatened or shocked. quite the opposite! I had two wires, one at 6 inches and one at shoulder height for 10 week old pigs. they all went to check it out, each one stuck their snout right on it, screamed bloody murder and ran backwards and then away shaking their heads. pigs know what an electric fence is after the first time. trust me. mine never got out, they did not root dirt up onto the fence to short it out...if you have a good box that wont happen anyway. I fed mine well along with the pasture, not scraps or garbage either. a good grower food not full of preservatives, they rooted up grass roots and stickers and lots of other stuff but given enough room they will not destroy a pasture completely. contrary to popular belief pigs do not like to live in the mud.
I always knew when one got pushed into the fence as they would bark/screech. they never tried to thwart the fence. if they do root up by the fence, just walk along and stomp the dirt back down to keep the fence clear. I also had a hot box, 3 joules output. the higher the joules the hotter the fence. I loved my pigs and they gave me relief from a nasty disease when they hit the frying pan. clean raised pork is the only way to go.
I was told they are not dogs, do not trust them, do not let them put their mouth on you or push on you, a good whack on the snout or back with a stout stick taught mine to respect my space and I never had any problems with mine.
and 40 bucks a piggy?? heck they are 100 bucks around here....good deal!