I have and use a 'shock' collar, or e-collar with my dog.
And, I recommended it to a lady I met in my clicker training class for her dog. She was totally against it in principle, however after 4-5 months of seeing us almost daily at the dog park, and seeing how happily responsive my dog was, she decided to bite the bullet and try one for her somewhat willful Lab/Greyhound mix.
Still took her a couple of months to actually use it though.
Once she did, and after she'd read how to properly use it as I'd told her from a professional trainers site loucastle.com
she was totally floored.
I believe she has only used it twice, and he actually recalls at her command, and he doesn't look tortured or fearful in the least.
THE problem with shock collars, and most of the people who are against them are based upon plain ignorance.
Without knowing anything more than the average dog owner, I also though they were simply used as immediate correction devices, dog does something you don't want, shock.
Unfortunately, thats the opposite of Training.
And obviously, how is the dog really going to know what you want, etc.
Training with a shock/e-collar is effective, is humane, and it does open up a whole different realm of interaction with your dog than solely positive reinforcement. And does not have to involve pain.
The key is, when you are doing it properly, you are not zapping your dog. You have a decent brand collar, with multiple levels of power, and you are working at the lowest level the dog can feel. Basically you are able to send a signal to the dog, and he feels nothing more than tingling sensation.
You are working on a feedback system that is not based upon pain.
The first and most important thing and reason I got the collar was for recall. After a couple of months of clicker training, with a respected teacher at that, I was still getting half-hearted compliance, and that wasn't acceptable.
Within 20 minutes of getting the collar on my dog, I had 95%+ compliance. And that was just one simple, pain-free session.
Took him to the dog park the next day, and no matter where he was in the park, even if a couple of dogs were scrapping and he wanted to watch, I could get him to come back to me with one call, verbal, no 'zap'.
And its been that way ever since, and frankly I kind of love to show that off. He's so good now that anytime a couple of dogs start to go at it, while he wants to join in the onlookers and watch, he will most often look at me for a jerk of the heard to come to me instead. He's learned pretty much to not get involved in the pile-on that occurs once a scrap starts with multiple dogs around.
Thats with the collar on, and off.
And that has helped immensely in all areas of obedience.
And for the record, most collars come with a pager button, which either makes the collar beep or vibrate, which is all I ever really use now, on the rare occasion I even need to use it.
The sad thing is that they make the cheap collars with only a couple of settings, and most of them are too high to start with for most dogs, and even if they don't cause real pain are startling enough to cause a yelp, and they don't really do much to educate the user on how to properly use them.