Bitman, I am a Lowrance user, and have been for years. I faced the same choices/dilemma on my 08 boat. I am running a 28HD at the console, and a 37C on the bow. After a year of use, for my fishing, I am better served with a non-HD unit and the Navionics mapping chip. For the TN/MS/AL lakes that I fish, including Pickwick, the Navionics is the ONLY map I need. Nothing on the HD mapping choices comes close to the resolution and detail. If you will use various maps, the HD may be a better choice for you. As to screen size, the best move I ever made was to put a 37 up front on a RAM mount. The difference in what you can see is amazing, as compared to the 27. Features are all the same, but I really like the bigger screen. Hope this helps—one mans experiences. Mike Whitten/Germantown,TN