I have the ones from MyLitCo.
Had a set on my old car for 18 months, no problems at all.
Had some on my current car, after 6 months on one side 2 of the 8 LED's had stopped working and the unit would intermittently flicker. I emailed MyLitCo and they sent me out a replacement unit within 24 hours of my original e-mail.
I had the festoon type bulbs before in my old car.. they were for for about 3 months until weird things started happening... randomly when I started the car the light out bulb would be on. If I turned the headlights on and off again, it would go out, most of the time - Sometimes it took multiple attempts... then occasionally my LED strip in my Hella Celis lights would stop working... again, really weird. I eventually found out the bulb warning was that NEITHER of my number plate bulbs would work unless you started the car and performed a rain dance (with the lights off, turned them on, then off, then on again) after which everything would be OK
Traced EVERYTHING down the cheap crappy festoon bulbs (which had the built in resistors..) - Replaced with the units and all is OK.
The Mk6 units are more expensive (you can buy these whole replacement aftermarket units for around £20-£25), they come with a year warranty from MyLitCo (who are very big not going to disappear overnight) and the Mk6 units are NOWHERE NEAR as bright - They look about the same as festoon LED bulbs - Pretty pointless!!
Here are mine - Mate took the photo.
