I've got 2 520C (one on the front and one on the console) and I absolutely love mine. I know how the use the general stuff on it. Marking wypts, finding wypts, ditches, drops, etc. Once you know how to use, you'll feel like a blind person with just a depth finder....... It's amazing how accurate they are with the chip in it of course. I have the fishing hot spots elite chip in both of mine and have borrrowed the navionics but I like the FHSE better than navionics.