I'm going to beat the drum (again) about why everyone with an iPhone or Android smart phone goes to the trouble of powering and bluetooth connecting a dedicated GPS unit to the Sena when the phone will do everything the GPS does and a lot more.
With the latest hardware you can run multiple apps at once on your phone that gives you more flexibility and simplicity of connections. I've got an iPhone 6plus that runs the following apps simultaneously if necessary, and all I have to do is power one device and connect one device to the Sena:
1) SW Connect - no need for $100/year or more for SPOT. - Free
2) Navigon - off-network navigation for roads (maybe CoPilot is better - certainly its cheaper) - $30 for Western US and free lifetime updates
3) MotionX GPS for internal tracking and navigating in more remote areas - it updates real time instead of 5 minute intervals on Spotwalla and provides cool features for documenting your routes - Free - for $5 you can enable custom map downloads from multiple servers including USGS topo maps, world topo maps, and others.... - this is freakin' AWESOME!. MotionX can also be used to plot your tracks from GPX files - super easy and works great.
4) Waze if you want to use it instead of a nav package - free
5) Music - free (pretty much
)
6) Phone
When I was in Mexico earlier this year on the ride that Beemerdons had set up (sorry again Don - we missed you!), one late afternoon we were wandering around the high hills (34 degrees!) and our guide had only a paper map that had yellow highlighter marking the route and no idea of where we actually were. The guys with Garmin GPS units showed a blue triangle on a blank white field that showed where we were but had no map on the device that showed any roads. With MotionX and the detailed topo map of Mexico that I had downloaded, I had the only device that plotted position against a map that actually told us where we were and how much further we had to go. It saved us from a lot of possible trouble that day.
I used the same setup this last week in central Oregon while riding in the hills around Bend and it proved to be great again. I had plots of roads and NF trails right on the phone instead of having to continually open up bulky paper maps and trail guides. When the week was over the guys I was with were convinced that this was the right way to go.
Sorry Ray for such a long-winded input, but in summary I'd suggest not worrying about a GPS and just use your phone for everything (of course assuming you've got a phone that supports GPS navigation).