I have a Elite 7 HDI on the bow of my boat. I was thinking about adding a Garmin 551 DV to the back. Should be easy to install and could be used by fisherman on the back. I already have GPS on the bow unit. I think regular 2D and DV on the back would be cool. Is this a good unit ? Is there something I should know? I already have another HDI transducer for the Elite 7. Would I be better off to purchase a Elite 5x HDI w/o the transduce. The Garmin would be a little cheaper, I am just not familar with that unit.....Thanks everyone for any information.....crappie1133