I've posted on this before and will again.
Our HO doesn't allow 6 foot fencing and no fencing can surround the property. All homes are on 1-8 acre lots, there are about 200 homes and 2 entrance/exits to the community. Traffic is residents, deliveries, and services.
As a guess, 80% of dog owners have e-fences including us. During our 6 years here, 3 dogs have entered our property, all three came from physically fenced yards/areas, I know because I returned the dogs. I have never had a dog come through an e-fence on a walk or other. On our normal walk we pass 11 dogs contained by e-fences.
There is a lot of wildlife but with a dog like Bugsy I don't worry. I also don't have to worry about dogs coming in as he thinks they are all 'fun'.
We will not have dogs teased or shot at so that concern is not applicable.
Bugsy's prey drive is through the roof, he has extreme pain tolerance, and although he is 'ours' now he was over two when he seemed start believing that Prior to then his independent nature was prevalent.
We spent months ensuring that he understood the boundaries and respected them. We took training him VERY seriously and it worked. He is 100% reliable on the fence. I have seen him go after deer and cats at full speed and pull up, scooby doo style even though he wasn't wearing his collar. His only transgressions were to go across the cul de sac and play with a friend. He did this intentionally in the early days of the fence, ours is quite sophisticated and has a warning sound that alerts if it senses the dog is moving quickly towards the boundary. B didn't even flinch when he was 'shocked', he just merrily went over and was playing with the golden.
Both DH & I felt the shock and in no way is it painful - it is like a shock off a carpet.
Bugsy can and has lept over a 6 foot fence, a four foot fence is a joke. E-fence was our only option and we were both skeptical that he would respect it. But he does.
Like many other things it is important to consider your dog(s), your situation with regard to neighbors, wildlife, other dogs, your options, and your dedication to application.
I posted in another thread that as I have traversed the 'net looking for a rescue GSP i have noted that they all state whether the dog is e-collar or e-fence trained and they WILL adopt out to homes that have e-fences. Other breed rescues will ONLY adopt out to yards that are physically fenced. I think this is very interesting as I am 100% sure that Bugsy is better with an e-fence than he would be with a physical fence. Just as he is better in a room with the doorway gated off than behind a closed door. We do think he is part GSP and that the coincidence of GSP rescues having no problem with e-fences suggests to me that there may be something about the breed that this containment system works better.
Lastly, once a dog is trained fully on an e-fence, it does nothing 'to' them other than define their boundaries.