I'm having my NT serviced by the dealer, and especially while it is under warranty, and I bought an extended warranty as part of their break-down cover. At the 600 mile check they had to adjust six out of the eight valve clearances. It's hard to say if it made a noticeable difference because the motor was still loosening up, but it certainly runs smoother now. The 600 mile check is a nuisance - first you can't open the bike up much and then, just as you begin to settle in with it, you have to take it in for a service; when what you want to do, just having got a new bike, is ride and ride. I have no idea what damage (if any) would have been done in my case if I left it to 10,000, but I just think it is worth having the service done as Honda dictate - if only because it ties them to their side of the warranty promise. The NT is a great bike though. Had it about eight months now, and it's running like a train.
Bob