We had an E-120 Chart Plotter on our sailboat when we were cruising. I also have an A-65
Chartplotter on the powerboat that replaced her.
In 2012, we bought our first IPAD and installed Navionics as a back up to the E-120 when we were cruising. At the time, they didn't talk to each other, but it was a great back up and did everything we needed.
We bought the
Power Boat 3 months ago and the A65 has a Blue Tooth option, which allows you to control the chart plotter remotely from the IPAD. That is a separate
Raymarine software, but makes it nice to use the larger
screen.
I find that the IPAD and the Chartplotter
Software to very different
animals and think the IPAD version is still a little clunky, but a great backup if the Chartplotter fails. I also use the IPAD Navioncs for pre-planning boat trips.
The IPAD version is updated anytime you connect to the
internet and you can make changes to the
Navigation Aids or any other bookmark (Fishing & Dive Sites) and share them with the rest of us. Because of that the information on
Marinas, etc if very accurate.
Also the IPAD verision only downloads charts of areas you want. So for instance you buy rights to all the US Charts, but you only download charts you are using to save HD Space.
The basic Navioncs Software is $9.99 and then you choose and
purchase the areas you need charts for. For instance, US Charts cost around $50 a year and is renewed annually.
The $399 you are talking about is a chip
sold for the Raymarine Chart Plotters, which has many more bells and whistles that will only run on a Chartplotter.
I used the Android Version of Navioinc on my
Cell Phone for a little while, but got frustrated. It is much better if the display screen is larger...
Good luck.