I have a couple of Helix units and have a Lakemaster card for them. It's a far superior map to the HB Basemap. I watched a video last night where a guy is using the HB Fish Smart app on his phone. IIRC you can buy individual lake maps through the app and directly download them onto the unit. I'd have to watch the video again to be sure, but I think that's correct. I remember for sure that you can update your units through the app, via Bluetooth connection without having to use an SD card. That will definitely be a better way to update them.

If you fish the same body of water all the time, buying the individual lake map would be the way to go IMO. As big of a tinkerer as you are, you could just make your own map with Auto Chart live, and load it on the Zero Lines card. I plan to do some areas of my home lake that aren't mapped well. It's bad that I have all this technology and don't use it to it's fullest. I guess it's time to change that for me.