I have G4 and G9. I modified my G4 to take auxiliary jack for Shure noise isolating ear buds ($175). Bottom line, I'm into long range touring (at least that's what I outfitted the bike to do). Ear buds hurt after 3-4 hours, and the music goes from amazing to an irritant. My modified G4 eventually failed on the road and I replaced it with a G9. If I knew then what I know now, I would not have done the modification. Also, if I were to do it again I'd use jacks with ability to switch back to helmet speakers when the ear bud jack is removed. My final configuration is use of a $40 Garmin application on my iPhone for navigation. The iPhone Bluetooth G9 link gives me telephone communication from my helmet, navigation audio, navigation video, iPhone sourced music (over helmet speakers); intercom with my wife's stock G4. The Garmin iPhone App gives me GPS location, mapping, highway speed limits and vehicle speed, etc, etc etc. When I want music on shorter rides, I put my iPhone in my pocket. The G9 establish a mobile Bluetooth link automatically. I wear the Shure ear buds using my iPod mounted in an X mount holder between my handlebars. If I get a call, I pause the iPod; call ends - un-pause.