What you might do is ask these questions on the main crappie forum under electronics and you will get better response to your question. I am partial to Lowrance but have used Hummingbird many years ago. All these newer fish finders are pretty much spot on and do their thing. I like the HD images they give you. I think the main weakness of all of them is their mapping software of the smaller lakes is lacking as no lake maps will cover every lake where you fish.