I run a vexilar FL 28. Great machine. Like Rocky said, they are wonderful for telling you that fish are there and NOT biting - so make a change. Here in walleye country we don't often see fish before we try a hole - they seem to come in. What you see also depends on water depth.
You might want to consider getting a unit that you can also use on a boat. Humminbird makes iceducers for at least some of their units. I bought a plastic utility box like an army ammo box, and mounted a humminbird 797 on top, cut a groove to get the transduce out, and put a small 12 volt battery in it. It has a flasher display mode. I also like that it has a GPS and lake map built in. I sometimes run this unit in graph mode, which gives me a better indication of the size of a fish. .
My preference? If I didn't have the vexilar, I could get by with the Humminbird. .
