I spent the money for primarily for reliability, then ease of use and a decent, cable-free design. The former is the most important as I do between 20 and 50 miles a day on unlit country lanes. It breaks down then I'm faced with a long, very dark ride home / to the station. Cars have a tendency to bomb along the roads in the dark and if they can't see your lights they're going to be in the middle of the road likely as not.
It's the reason I sold my old home-built halogens (1st set) and then my HIDs in turn (generic make then Lupines) – after being stranded for the third time when a cable / ballast / bulb went I got them repaired, flogged them and went for decent LEDs with a company that I know has decent customer service.
My 2009 Maxx-D has seen 4000+ miles of use. Even in the summer it's on low to help traffic see me. Hasn't missed a beat – the battery power was waning a little so it went back for a (free) tune-up. Came back good as new. My Enduro-Maxx has been faultless
If I could afford to risk DealExtreme then I would have – just that amidst the rave reviews there were too many stories of failures (and I can't wait weeks whilst they get sent back and replaced).
Just my 2p's worth.