I have an echomap 73sv and its pretty good, that is if you can deal with garmins active captain and its "issues". Case in point, had it working for a while then traded my cell phone in for a better one. Finally got active captain to play nice then the phone just died. When I got a new one under warrenty this is where the real mess came in. To make a long story short, after setting up the phone and resending all the maps from active captain, I kept getting a map is locked error when I booted the unit.
I found some troubleshooting tips online and removed the SD CARD, booted up the unit with no issues. I ended up having to buy another SD CARD so that activecaptain could reformat it. Now, had I saved the adaptor that comes with the SD CARD I could have put it in my laptop and done the same thing without paying $40 for a new card.
Finally, after much effort the activecaptain app and the unit syncs everything.
Hope this helps.