J&M will have SOMETHING for you if you want/need to connect about a billion devices at once. And a hardwired system means no searching for a connection when you want to talk to your passenger so it's much more instantaneous.
Myself, I got a SENA SMH10. I love it. I don't mind waiting 2 seconds to talk to the wifey, she syncs her music to hers, I sync my music to mine.
For ipod + GPS, that's tough on the SENA. Easiest option would be using an android phone as an ipod/gps. It all plays through one device. Next would be having a GPS that you load mp3s onto, and syncing that as a "media player". You can STILL then sync your phone as "phone".
My Solution, my wife upgraded her droid phone, and gave me her old droid phone. I bought a 32 gb microSD card to expand the memory. Bought Sygic GPS for it for about 20 bucks. It downloads the maps right on the phone so you don't need data connectivity. Then synced all my itunes stuff to it with "doubletwist" app. So used droid phone, about 50 bucks in GPS app and microSD card, and I have an "android touch" that I mount to the bike to use as a GPS and ipod. I can put audio books on there, podcasts, I can use ANY android app by downloading them through wifi, and I'm happy. And cause I'm NOT using it as a phone, the battery lasts a LONG time (unless I'm using the GPS, but then I just plug it into my powerlet to keep it going)
Alexi