Ive seen lots of threads on this but seems to unclear. How do Garmin users feel this will be for freshwater bass applications (I realize this comes pre-loaded with coastal maps and CV51 ducer). Can they be networked and use one lakevu map card to display freshwater lake maps on both units, or will I have to buy two cards? How will the graphing be in freshwater...20-40...drop shotting smallmouth etc (video game fishing)..