Thanks for the feedback (even Callum

).
A little more info...
Invisible fence is a brand, like Kleenex. Unfortunately, I don't know what the name is for the generic category like "facial tissue" in this world, so "wireless fence" was my effort to come up with one. Since it has a wire, it's not a good choice
However, to address the things that have been brought up...
They are indeed buried in the ground, and they rely on a shock ("correction") for the dog when it goes past the line. They both use an audible beep to alert the dog that it's in the fence area; that, of course, is painless [img]smile.gif[/img]
Invisible fence (IF) has one setting for shock -- on or off. Pet Safe (PS) has ten, from mild (I felt a slight tingling) to potent. And it can be adjusted, depending on the dog's personality and tendencies.
They both rely on a wire buried in the ground. Obviously, that's a point of failure. PS has a signal in the base unit that tells you if the connection has been lost (the wire's been broken). To my knowledge, IF doesn't. PS can also come with a battery backup in case the power goes out.
Apparently, once the dog has been trained, he'll stay away from the perimeters on general principals. Other friends have talked about turning their fence off for a couple of months and the dog still behaving as if it were live.
A lot depends on the personality of the dog, apparently. I'm not sure if that's going to be good or bad yet
I think PS will bury the wire inside a PVC tube, so it's more protected from the elements. I don't believe that IF is planning on doing that. PS also planned to call MISS DIG, our local authority who will come out and identify all the underground wire and cabling runs so you can avoid them when doing work. IF didn't even mention that.
As for real fences, I used to have on in the back yard... and I hated it! A nice picket fence... with all the additional hassles of painting it ('cause the paint doesn't last, which may well be my fault) and trying to mow around it (which is just a royal pain). Of course, using the weed whacker to get the grass near the fence would chip away paint from the fence as well, so... not in my plans.
A dog run would be a possibility, but we'd lose a fair amount of the back yard. He's going to be a decent-sized dog when he grows up... 65-75 pounds or thereabouts. What's that... 30-35 kg?
So... I'm still interested in thoughts, opinions, and perspectives.
Thanks!