I've had the conversion since late '06. I've never had any problems with it until recently.
Over the past couple of weeks, I started to get the fault on the dashboard telling me that the head light is out. I was able to clear the fault by turning the key off and then on after a couple of seconds. Over the weekend, on my first long'ish trip, it occured more often. By the return leg of the trip, nothing would fire the HID. I rode the majority of the trip with my brights on. This morning I went out to move the bike and the HID fired up and continued on for about 3 minutes until I moved it and turned the bike off.
I've put about 5,000 miles on the system. I've had it on for 6 hour rides of about 300 miles with out fault. The only difference is the weather, in the 90's this weekend and the distance of the trip, right at 600 miles.