For what it's worth I just put the 788 ci hd down imaging at the bow of mine. I have alway's had humming bird's until I bought my new boat that was equipped with Lowrance. Lowrance will not work on any unit that is 5 years or older. I just went through it with them. The gps unit is compatible with the I-pilot trolling motor if you get the 788. The 500 series is not. also the 700 series will connect to a bigger unit when I put one at the helm, and waypoints can be shared between the two units. That comes in handy more on inland lakes,I use the gps on my fishfinders for navigation and use a handheld as a backup. For me hands down hummingbird. I have had high quality units from both companies and lowrance is no match, especially with them refusing to work on there own units over five years old.