1. Cost. You probably already have a smartphone. All you need to do is install an app and download some maps.
2. Convenience. Since your phone has internet access, it's easy to download routes and map updates.
3. Finding fuel stops, places to eat, etc- online info is usually more up to date than a GPS providing you have data reception available.

1. Harder to control the screen with gloves on.
2. Raindrops hitting screen can make it zoom, change functions, go crazy. (Never had a phone that was usable in a hard rain)
3. Phone must be connected to external power due to display running continuously at high brightness. 
4. Under bright conditions, the USB charging rate may not keep up with the phone's power consumption, causing the battery to run down.
5. On hot days, the phone may overheat and shut down.
6. Phone may be waterproof, but the USB connector is not. Phone might have to be unplugged if it rains.
7. Most phone app displays are not optimized for motorcycle use- buttons and text are too small, buttons often located in inconvenient places, too close together. 
8. Bike vibration can damage the phone camera unless you have a special mount.
9 A good phone can be much more expensive and difficult (think about transferring data) to replace than a dedicated GPS.

Looking back, the times I have most needed a GPS was when trying to navigate through a big city during a downpour- absolutely needed to have it working with voice prompts. That's also when a phone is most likely to fail. BTW a phone that's not working isn't going to send texts or make calls either.

1. OsmAnd is available for both Android and iOS, so only one app to learn and support that will work for everyone.
2. You can download and install a free version with up to seven states of map coverage which meets the needs of most rally attendees.
3. Very easy to download and import GPX files.
4. Can display and navigate both routes and tracks, plus alert for nearby waypoints in the GPX file, so it works well with existing MSTA event GPX files
5. If you want unlimited map updates and downloads, you can subscribe for only $9.99/year.

I recommend a dedicated GPS for use with MSTA routes. Some attendees don't have one or just prefer to use their phone, so I want to offer them a phone app with support so they can come to my event and use our great routes without spending extra money.
Attendees are free to use whatever phone app they wish, but supporting a variety of other apps is beyond the scope of what my volunteers can do.

1. OsmAnd is very "destination oriented." On loop routes where the start and finish are close together, you need to be either very close to the actual starting point or already into the route when starting navigation- otherwise OsmAnd will cheerfully declare you already at the finish. Done!
2. Voice prompts are very chatty, alerting you to relatively gentle curves in the road as well as turns. Railroads and pedestrian crossings are frequent voice prompts- often prompting when the railroad is more than a mile away, even when the crossing is not on the route. Info on how to disable some voice prompts can be found HERE
3. Don't rely on the given time or distance estimates given for the current route- they can be way off.
4. Off-route recalculation is not always timely or optimal.
5. Maps are excellent and map display is very clear.
7. OsmAnd can easily do turn by turn navigation from a track, as well as a route.
8. For individual GPX files that contain both routes and tracks, OsmAnd does not allow you to choose between them- it just offers you what it calls a Track.
9 Individual GPX file that contain only routes or only tracks are treated interchangeably- Both can either be made visible on the map manually follow or be navigated with turn-by-turn instructions. 
10 ADV riders can navigate the main route and set alternate tracks showing hero sections etc, to show on the map simultaneously. 
11. All waypoints in the GPX file that exist independently of routes will be displayed on the map and generate voice prompts in their vicinity. Points in routes that are set to alert for dedicated GPS units but do not exist independently from the route are ignored. 
12. Battery saver tips from Jon Juracich- There are 2 settings that can mitigate the battery-usage problem:
- Profile - Navigation Settings - Animate Own Position: set to OFF;
- Profile - General Settings - No animations: set to ON.
- If you use a Quadlock wireless charging mount- get the version that runs off 12 volt bike power rather than 5 volt USB. It will keep your phone charged much better!
These settings help a great deal - my phone will generally stay charged or mostly charged when running off the bikes power. They also don't seem to affect the apps functionality - at least that I can see.