I'm looking for a decent sonar/GPS combo for in the $500-$700 range. Trying to avoid drilling holes in the transom and decks with external antennas and transducers so I'd like a thru-hull and internal GPS antenna. So far I've found the Lowerance LMS-334c and LMS-339c units. I checked the out at Cabelas and they are the screen size I want.<br /><br />Anyone using these units? Any opinions about Lowerance combos? I'll be using it in everything from clear to murky freshwater and brackish water on the Chesapeake, all less then 200 feet deep.