Here is 2 cents from my side. If I had my druthers, I would keep my little M68c on the dash, and have a good (without gps) finder up front with the 'ducer on the foot of the trolling motor. I like having all that info from the M68c to get me there, but want something made just for finding structure/fish up front. Have found when you get a combo unit, your gonna be missing out on one side or the other. Your either gonna have a kick butt gps or a great finder, but to have the best of both worlds in a combo, your gonna have to really dig deep in the visa account. As far as what unit I would have up front, Lowrance, Eagle, Garmin, Ford, Chevy, Dodge.....well you get my point.
A gun in hand is a lot better than a cop on the phone.