My dad uses the prong collar on Samson when he takes him for his daily walks. It actually work better than using a regular collar. Sam's neck is just so thick. Dad is able to control him better with it, especially making him stay right at his side. Sam is 125lbs (not overweight!) and you know how dogs will pull at the lead if they spot a cat or a kid. (Sam does because he just wants to say "Hi!") My dad is just 5'3" and weighs maybe 20 more pounds than Sam.
The one time my dad didn't use the collar (because the obedience instructor told him not to), Sam stepped in front of my dad during a walk. Because they were going downhill in the middle of the road in our neighborhood, my dad couldn't move away in time and tripped over Sam. My poor 72 yr. old dad scrapped his chin and his legs, on top of injuring his right knee. Since he was walking him pretty early on a Saturday morning, no neighbors were outside to see this. Dad had to hobble back to our house. He did say that Sam sensed that he was injured and walked very slowly with him, watching his every move.
So yeah, Dad uses the prong collar from now on during walks only. All other times (like the dog park), we just use a regular collar.
If used properly I think they are fine. And I am the kind of person , who if I use a piece of equipment, try to "use it properly". I started using a prong on Skippy because I didn't have him trained perfectly to "walk quietly" on a leash (I didn't know how at the time) and I still wanted to be able to take him places without having him pull me everywhere. He weighs 110 lbs (and no, he is not overweight as verified by the vet - he is very tall and heavily muscled - more like a bloodhound build). I put a prong on him, took him to the local soccer game, he pulled once and from then on walked quietly beside me. I don't jerk, or pull on it. He doen'st mind it because he gets very excitied when I get it out because he knows it means he is going to get to go somewhere. I didn't start Emilu on a prong, because I was taking her to obdedience class and wanted to "do it better". One year later, and with a different instructor, we were back to a prong for the class - she is an instructor who puts certain dogs in prongs because you can just train them better at first. We weaned from the prong after about 8 months, before we went to our first show and she has only had one on very occasionally since then (if control is more important than "proper etiquette") I have seen chain collars (or "choke" collars) used much more incorrectly and more frequently incorrectly than prong collars. I don't think that any dog should use a chain collar unless the person and the dog has been properly trained in it's use and the dog has some semblence of "heel" in its vocabulary.
I use prong collars on M&J to
1 keep them safe
2 keep me safe
3 keep other people safe
You must know how strong labs are, and although they are very obedient 99.9% of the time, ignoring squirrels, cats, other dogs, bicycles, etc , there is always that possibility that they pull away; they are dogs. Either one could pull my arm off with a regular collar, and I walk the both together. Since I walk both of them in a residential area, I need to have 100% control whenever they are out of our yard.
I have used Martingale collars which worked well until last year, they wanted to greet an elderly lady and I was unable to hold them. They did not hurt her, she welcomed their kisses, but I can't let them run up to strangers. They also may pull to greet children which I can't allow unless I know them. I have Gentle Leader head harnesses for both of them, but Mitzi freaks out wearing it, and Judy has a facial spasm which is aggravated by hers. I bought Gentle Leader no pull harnesses for both of them. That was fine until a neighbor's new lab puppy ran up to them to play. I was not able to hold either of them.
So that leaves a prong collar which controls 100%.
They do not seem to mind wearing them and usually we go through our whole walk without the collars tightening, no pulling - they don't feel anything. When the collar tightens, the dog is doing the pulling - not me. People have even remarked to me how cute they are wagging their tails in unison as they walk. So they must be enjoying their walk.
I also let them run free on State Park land by a lake so they get Laika-type walks/runs too.
I use a prong collar on Jimo (all 107 pounds of him) because I am 9 months pregnant. We are working on him not pulling on the leash, but in the meantime my DH was not willing to take the chance that he would pull me over and I would fall.
Amazingly, he actually loves the collar...he knows not to pull when he's wearing it (and behaves perfectly with it on) and gets so excited when I get it out to put it on (just cus he knows it's walk time)...once I am no longer pregnant we will go back to the harness...but for now...it's not a risk I am willing to take.
Shiner is ok with just her harness, she knows not to pull.
Because I couldn't walk my two 95 lb. boys together. They're totally effective for them. They only wear them when we're leash walking, and it does wonders. They are much more manageable when they wear them, and don't pull at all.