I am a huge fan of the invisible fences. Aside from not having an ugly fence that you have to mow up against, I have found them to be very good. It is critical that you do the training correctly and even take longer at removing the flags than they may say. You really want to reinforce the location of the boundary.
Over the years, we have trained a lab, two GSPs and two mutts on it.
Our lab was an escape artist at our old house. Our six foot, very expensive fence was a mere inconvenience. Houdini had nothing on this dog. We never witnessed the escapes, so we don't know if smoke and mirrors were involved, but she would wait as long as it took for the humans to get tired of watching her, and away she went. After we moved to a new house and put in an invisible fence, no more escapes.
A good friend of mine didn't think an invisible fence would work on his dog, so he spent thousands on a fence that met the "covenants of the homeowners association" but pissed off his neighbors. I kid you not, within 30 seconds of him releasing his Brittany to the new fenced in yard, the dog ran to the back, jumped the fence and was gone.
Dogs have big enough brains to figure out solutions to physical barriers such as fences, but they don't seem as adept at electronics.
If you train your pup on the fence before it goes to training, you may want to do some reinforcement training when it returns. I doubt you will have any issues at all.
