Have used a Vexilar FL-8 for years and love, wouldnt fish without it! But your right, in anything less than about 8 feet of water it seems like it spooks the fish. When its that shallow I dont use it much anyway. But over 10 ft deep, there is nothing like it!
They are very simple to learn to use. Bottom will be a red line, your jig will be a red line, fish will start out a green line on the outside edge of the cone, turn orange, then red when directly below the xducer. when the red line of a fish meets the red line of your jig set the hook... he's got it!