I have an Aqua-Vu And found it doesn't spook fish at all. You basically have to bump the camera into them before the spook most of the time.
I spent the extra money for the Aqua_vu figuring they have been at it the longest, they know what works and what doesn't. Plus I also wanted the ability to record what I was seeing.
As you would imagine, the clearer the water, the better they work. It's a little hard to understand what is going on at first, but as long as you can keep the bottom is sight untill you get the hang of it, it just takes some practice to control.
Here's a few short videos I took last summer while playing around while fishing was slow. Goes to show that just because they aren't biting, doesn't mean there are no fish there.
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I think it was money well spent, if only for the entertainment value when the fishing is slow.
http://youtube.com/watch?v=q6aowSAMfpI
http://youtube.com/watch?v=2eMU9ipYumY
http://youtube.com/watch?v=YOPdHnL9hQA
http://youtube.com/watch?v=3rhGE8h9AZY
http://youtube.com/watch?v=NExpXVVeoEA
http://youtube.com/watch?v=CfxfmLICYnE
http://youtube.com/watch?v=qHkA4o_3FEE
http://youtube.com/watch?v=V33MfrL2Fao
Steve