I went with the Xi5 because I wanted to be able to use the functions offered within Lowrance. I was testing out trolling last Friday on a fairly large lake but that is mostly shallow. I was having to follow the channel and it was becoming a pain in the rear because I was facing the back of the boat and I would occasionally venture into shallow areas and drag bottom or hang up. Then I remembered I could set routes within my Lowrance unit and the Xi5 would guide it. I used the map on the screen showing the contours and plotted a route, then hit navigate (can't remember the exact verbiage) and just paid attention to my poles for the most part. Worked like a champ. I also tried this in a river with lots of bends with no problem.

I think it really all depends on what you want to do. I'm a technology guy so I like to take full advantage of what's available.