One thing to consider is data, not in the sense of cost as most phone contracts come with an abundance these days however signal is a problem.
Google maps, Waze, Apple maps etc do not work on downloaded maps, instead they download constantly. This year I found that in the lakes, up through the central lowlands & back through the borders region into Northumberland these packages did not work consistently as there would be little or no data signal to download the next section of the map.
Camping in the Etterick region was like being on the moon as far as data went. Even when there is a phone signal you may find that the data is insufficient to populate the map.
If your in an area that only offers 2G, GPRS or EDGE, the software may not function correctly.
A better option may be to download Tomtom, CoPilot, Garmin Street Pilot etc onto your device, then you only need GPS.
The latest iteration of Tomtom seems to be widely slated at the moment however these are just examples, there are quite a lot of app's that use downloaded maps instead of data.
For sound, I use a Sena SMH10, haven't been able to fault it. I did order the SMH5 initially however FCMoto offered me the 10 at a discount as the 5 was OOS, result!