I bought 2 HID kits from DDMTuning.com a long time ago. I have had 3 failures, all on the right side. The first was NOT a ballast, it was some other component. I bought another kit and randomly replaced a part (there are 3 or 4?) and got lucky, I replaced the right part.
The 2nd 2 failures were ballasts. You can buy 2 ballasts for $25 shipped on Amazon. It's a pain but my lights are amazing. I do get people flashing their brights at me some time, oh well. That just means they see me. I'd rather **** them off than die.
My high beams are useless unless leaned over in a corner or going down a steep hill than goes right back up. I can live with it, the low beams are like freakin daylight. I also put on dual PIAA horns that sound like a 1975 Cadillac, they are LOUD and if I'm using my horn, I want it loud.
The stock headlights are only OK, LED is not ready for prime time. HID is complex and can be troublesome but now I know what to do if one fails. It used to scare me, I wasn't sure of how it worked, so if it broke, I wasn't sure if I could fix it. I've seen it enough and it's just a process of elimination anyway. If you get them and something fails, I'd start with the ballast, based on 2 of my 3 failures being ballasts. I've also done a fair amount of googling and the ballasts are cheap Chinese garbage and I couldn't seem to find more expensive ones that were better, so I bought the pair for $25, fixed my most recent problem and can swap in another if needed in about 30 minutes.
I would describe them as the best mod I've done to my bike and I have the horn, a Seth Laam seat, unlinked brakes, 2 different flashes, a Garmin 220 GPS and a rather nice radar detector setup. So yeah, you could say that overall, I am very happy with them.