Ill share my experience since I wear the Freedom 4. Short version is Yes it absolutely works!
Some quick background on my dive conditions. 1st, no I dont work the company or I would be wearing the updated new Freedom 7 at no charge, so this is just my own thoughts. I dive in Jupiter Florida. Probably one of the most aggressive shark populations in Florida, due to the large population of spearos and cross current as the gulf stream starts to move further away from shore and the abundance of big fish. I have been spearfishing here for about 10 years and have shot plenty of dead bleeding fish that our sharks usually want. I never drop my fish if a shark is approaching because, hell just come back up to the food source(me) and wont stop, so I always keep my fish.
I usually dont turn on my shark shield until after I have shot my first fish and then if viz is good at 50+ feet, I may not turn it on until I see my 1st shark, since it also can be an attraction in my opinion.
In my dive location, the biggest problem we have is with bullsharks. They tend to stick together in groups and when there is 3-4 and you dive solo, a little help from the shield is nice. Most of the reef sharks seem more solitary and by closing the distance and either barking at them or butting them, they will back down and hold off. Nurses rarely move and just sleep. We dont get many hammerheads, but if its January and the Lemons are around, you need to really pay attention since they are ambush sharks, and dont circle or bump like the reefies and bulls. Again, just my own opinion in my area that I dive.
When I have had a problem with sharks that wont back down from a punch or a bark, the shield does work. They will keep taking runs into you, but really cant focus on the dead fishs exact location next to you because they are not right on top of it. As the shark comes up, at about 10 feet away it will clearly hit the irritation field and turn as if to bounce off of it. They usually will circle back immediately and try it again and usually several times. You will still need to take aggressive action towards the shark(s) and back it down. If you dont hell come at you from the top where the field is not as strong. Also its just an irritation field, not a vault. If the shark gets a full run like Lemons do, your going to get bumped and hard, and the shark is not going to turn. Dont wait, get aggressive at the first siting, chase the shark, and back him down so he knows you arent going to flee.
The shark shield is just like a pony bottle. Its not required, but it gives you a huge amount of confidence when solo spearfishing, that you can deal with a problem, remain calm, and not bolt to the surface and embolize. Panic kills. The shield instills additional confidence that you can deal with a shark problem, but its not a shelter.
Couple of other notes. 99% of the time when the boat engines show up to get you, the sharks leave so you have as much time as you want to turn it off and calmly climb up the ladder, its not a Jaws movie. If you do grab the metal ladder and the shield is on, you and others will get shocked. What does the shock feel like? It doesnt tickle, it hurts. But it wont kill you either. You need to have every piece of exposed skin within 2 feet of the whip completely covered with neoprene or you will feel the light shocks. If you have short booties and a short wetsuit that rides above them, youll feel the irritation.
If you dont spearfish, you dont need a shark shield. If your not in a known shark population area, you probably dont need it depending on your hunting patterns. I have no experience with great whites, makos, duskies, spinners, or other types of sharks since I just dive/spear in a very limited area. You can PM me if you have specific questions.
