don't know about for iPad but have Hema 7 Navigator GPS in car. I checked on Hema website and to download to phone from them was about $600.00 that is why I ended up getting GPS maybe prices have come down......
I bought the Hema Explorer app and the Great Desert Tracks maps, what I found was it wouldn't allow me to zoom in past 1x before it switches to the terrain/street maps layer so it was difficult to read/see when sitting in the drivers seat.
I figured I've already given Hema money for the maps so I found a torrent of them and used a free app called PDF Maps, was able to copy the geo referenced maps in .tiff format into my iPad and then used PDF Maps to display. Allows you to zoom right in and easier to read and has basic GPS functions like trip recording.
I'm not sure if the 4WD Hema app has this same problem, but was really annoying that I couldn't turn off the street map layer and I would of just torrent'd it in the first place if I knew it had that limitation as it was a waste of money.
Also another thing they didn't advertised was that yes you can sync recorded trips of other people from the Hema cloud into the app but unfortunatly it doesn't sync or cache the photos associated. It would be amazing to be able to see photos of points of interest that others have shared when they're out touring.
So yeah in summary, the Hema explorer app is garbage and would be intested to know if the 4WD app is better. You can do everything the Hema explorer app does with PDF Maps and WikiCamps for camp sites.