Cant speak for the MG as I haven't used one, Don G is a pretty good source of info, he aint gonna say it without knowing what he speaks of. Spot lock on the Terrova leaves a lot to be desired but for me its not a big deal, if that is important to you then the MG may be a better option according to reviews. As far as trolling and linking to the Humminbird I find the ILink is hard to beat and intend to have the new one coming out that will be auto deploy and stow.
good luck.