Two years ago I got one of the things and have used it under certain conditions. I read a bunch of articles and one in Crappie magazine and most were really favorable. In the article in the magazine the guy, who was a guide and I can't remember his name, said he was using it to work a deep bluff for crappie. He went down the bluff with it on and caught 10 fish, went back with it off and caught 3. He made several passes like that and with it on the caught about double.
I have used it when spider rigging mostly and it seems to help some. This spring we were on Kentucky lake and fishing is two boats. My friend and I were both spider rigging with 6 poles each and using almost identical baits. It was a really tough day and I had something like 15 or 16 keepers and he had 5 or 6. We both had 797 depth finders and were running the same speed. depth etc. That was the only difference we could see.
I wouldn't recomment anyone on a limited budget spending the kind of money they ask for because I don't think it makes a huge difference all the time. For instance, when they are in the bushes you don't need it. I'm going to try it night fishing soon and will post what I find. I've about gotten the depth finder under control, or at least think I have and will strart experimenting with different programs on this and see what happens. If you have the money and want another toy, go for it. It's like anything else I've found in fishing. It will take some work and experimenting to get the most out of it. I do feel from my limited experience that there is something to it and it helps, but I can't give specific scientific data to back it up.
Hope that helps.
By the way, when I first got it and used it a couple of times it got where it would not take a charge. I called the company and they replaced the unit immediately (within 4 days). They give really good service.
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A day late, a dollar short and two drinks behind.