Mandy - did you train your dogs? If so, is it easy? I'm thinking about going to PSP to purchase one and then ask the people who did my yard if they'd install it for me.
The only one I have with a collar on for the fence is Mia and she's in an enclosed fence. The way I trained her was just a shortend version of how you'd train a dog who was learning the fence in a wide open area. Essentially, I just had to show Mia where she could go (anywhere inside the fence) and where she couldn't (right next to the fence). Because I had a barrier already in place to work with, I didn't really have to worry about her running through the underground fence. She caught on pretty fast that the warning tone meant stay back or you'll get zapped. I just had to reinforce to her that backing away from the fence was a good thing as soon as she heard the tone emitted by the collar.
I lead her around the perimeter on leash, giving her treats to show her that the yard was OK and then led her to the fence until the tone sounded and then backed her away from the fence. When she was comfortable with that, I let her wander around on her own, but the first time she got zapped, she was afraid and went and sat in the barn next to the water pump and wouldn't move. I had to lead her around again to show her the yard was safe, throwing sticks and tennis balls for her, etc. By the second time she got zapped, she figured out that the warning tone meant get back ASAP and because she alredy knew that she could wander around the dog yard safely, she'd retreat to the yard--no more digging under the fence!!
I have my field set to minimum (which is only about 12-18 inches of shock zone) in order to just keep her away from the above ground fence. Obviously without a barrier, the field should be set to something much wider to keep a dog from running through (at least 10'). At full speed, a dog could easily clear the 12-18" zap zone without even blinking (not a problem in my case as I have the above ground fence).
You really don't need someone to install if for you. I did a relatively small fenced area along with the perimeter of my barn so the dogs could have indoor access in about a half hour. It really is quite easy!
The hardest part was figuring out how to get the collar charged and then going through the test phase to ensure the collar was working properly and the dog wasn't getting zapped by false signals from an alien source.