I have the XTAR D26 1600...and love it.
The first one I got about a year ago...had trouble screwing together...and then the light switch failed.
I shipped it to China [cost as much as the light...~$68 for a new one]....and they just emailed last night to say it was fixed and on its way back to me, under warranty.
In the meantime, I bought a new one from the same place...www.lightmalls.com...and it came with a much easier to screw together case.
I am now waiting for the repaired one to come back
Does yours ever turn itself on? Mine CONSTANTLY finds a way to turn itself on. I combat that by making it my primary, but if I clip it off, or it's not on the top of the bag....its on by the time I get back to it.