1. Totally love my '07 919 and yes it will do it all. See #2. Yet, in about 30,000 miles of riding I have only seen a couple of them on the road and only had two people recognize mine. They just never caught on, for whatever reason.
2. After a 14-day, 6063 mile ride I can confidently say that the Spencer seat can handle the hours. Before, my butt was on fire a few hours into a ride on the stock seat. After the mod, 10-11 hours a day for 14 days and I did not want to get off when it was over. My hands... another story.
3. +1 to whoever said wear the earplugs, even with the speakers. You can still hear the music, your ears won't be ringing after a ride, and it's SOOO much more relaxing on longer rides.