I am looking at depth finders for the front of my boat. I have a hb 570 in the middle of boat now, I use it motoring then spin it around to use on the front. I have to turn around to see it, and the xducer is on the transom. Not ideal but i make it work. I'd like to have a unit on trolling motor, maybe di, gps with mapping. I have a handheld gps that I use now. The gps on fish finder would be more for mapping. My question is do I need a unit with 2d sonar or will di only be fine. The one I've found on sale is the lowrance elite 5 dsi, it has gps, mapping and di but no 2d sonar. Thoughts will be appreciated.