I had (past-tense) an 8GB mini-SD card in my Zumo GPS with about 1,860 songs on it. I just upgraded to a 32GB card, which works fine. I assume with a card 4x the size I can download 4x as much music, so it would hold close to 8,000 songs. I'm not all that knowledgeable about MP3 and iPod and Bike MP3 and so on, but it sure is simple to have the MP3 as part of the GPS and run everything through the AUX. If you're going to invest $$$ in a GPS, getting one with MP3 is the way to go for me.GPS claims they play MP3 but I never see what the capacity is. I have near 8000 songs on an Ipod and 3 old Sony HD5 players. I use them to the aux cable. I seriously doubt GPS players have much capacity. I go 10 weeks listening to music 9 or more hours a day to go through 8000 songs.
Jason,Android phone with Google music, maps, as well as the actual phone bit mounted to the handlebars. Bluetooth (A2DB) in the helmet.
I have run power to the mount and could extend the Auxiliary cable there as well, but with Bluetooth haven't yet had the need.