I have been looking at the humminbird units and they sell the 788hd si combo for $700. It has side imaging but not down imaging. They also sell the 597ci HD di unit for $650 that has down imaging but not side imaging. I wished I could spend more but $700 is my limit. I was wondering if someone who had a unit with both could help me out and tell me which one would benefit me more? Thanks for any help!