Personally, it seems not quite as bombproof as my Muyshondt Aeon, as it weighs less than the Aeon even though it's slightly bigger. From the front you can see that the walls are thinner. There also seems to be a bit more play in the threads in my version (123) versus the Aeon.
Of course, for the price, I would expect the Aeon to be built better, and it is. The 123 has a much more usable and I think nicer beam, with a more pleasing (less green) tint with no rings. It's a solid feeling light though.
As for whether it will last for the long haul, I plan to abuse mine as usual on a daily basis of it living on my keys. I hope it can handle it (it should). If I break it (which I doubt), I'll report in. So far, I am very impressed with it from top to bottom and it's now my new EDC.
The worst part about it is that many of my bigger lights are nowhere near as bright as the 123. Now I'm on the hunt for another that it brighter and throwier (is that a word) to complement the quark mini. Kudos to Dave for such a great light!