Wanting to put a fish finder on the pontoon boat for our use on the large TVA lake we live on. I've narrowed my choices down to a Humminbird Helix 5 with Chirp Di GPS G2, or a Garmin Striker Plus 5Cv with Cv20-TM transducer. Any one have any experience with either of these units. Want to stay in the $275 - $300 range.