My bike has over 70k on the clock. I follow the maintenance schedule, and have not had a SMC problem. The left side valves needed adjustment @ 48k, and the right side @ 64k. I've replaced the left headlight bulb numerous times (exact count is in my maintenance log), and the right side bulb once. I've also replaced the clutch switch, front brake switch, rear outside flange bearing.
My wife's ST1300 has ~ 10k miles, so it hasn't needed anything outside of periodic scheduled maintenance. I change the brake fluid and oil in her bike once a year even though mileage wise the oil doesn't really need it.
I am very happy with the ST1300 & wouldn't change my decision to purchase it if I had it to do all over again.