My questions is: any preference on which to choose, if either, and why? Any experienced opinions would be greatly appreciated.
Lowrance Mark 4-HDI with chart plotter marked down from $542 to $234
http://www.amazon.com/gp/aw/d/B00EVI...cRL&ref=plSrch
Garmin Echo 551 dv Worldwide marked down $420 to $249
http://www.amazon.com/gp/aw/d/B00EVI...cRL&ref=plSrch