It really is not that bad, as I understand it. You select a route on your phone with the Rever ap, either one you download or one you make or have made from previous trips. Then plug your phone it, transfer the maps from the phone Rever to the Spyder Rever, and the GPS on the Spyder does the rest. There is no data usage, only the satellite links.
You can do the same now to your GPS, Garmin. Example, I downloaded some maps of routes for the upcoming Maggie Valley trip, from the host website, kind of. Then used a totally different ap to send it to my Garmin, when I get there, hopefully it worked, time will tell.
The advantage of the new system is that it is using the same ap on both devices, therby much less chance for corruption of the data.
Joe