I own a x51 pro lowrance unit boat and all new in 2010 i have never been able to see fish arches even with experienced anglers couldn't make it work so i'm ready to move on to a better one.I would like a SI unit for my main finder and the trolling motor unit with GPS i think i like Hummingbird but i want to know which brand would i spend the least amount on equipment i'm working with $2000.00 thanks for any advice.