>>>How long have you had them so far?<<<
I've had the low beam H7 in for a couple of years. Before that I installed their H4 on my Suzuki DR650. That bike goes out into several State and National Forests on a regular basis, (fair amount of pounding) and has been working great. http://stores.advmonster.com/h4-r3-led-headlight/
>>>I'm curious about the longevity of LED's.<<<
They claim 30,000 hours but who knows. Heat is one of the main semiconductor killers. The mesh braid heat sink appears to be working well.
LED bulbs have three heat sink options, mesh, aluminum fin and fan. I made the decision not to go with a fan. Though probably reliable there is no way they'll last as long as the LED, especially on the dirt bike. An aluminum fin heat sink will make for a neater installation but I couldn't find one as good as Advmonster's.