The only EagleTac I own is the D25A mini but I have held and operated other similar lights at the same time........ie: the Quark mini XP-G and the Quark mini XM-L. I believe EagleTac's XM-L version is the new titanium and is more $.
This is what I think: Run time will be no different between the two.........just that the XM-L will put out 10 to 15% more output at high than at the lower modes and be basically identical in efficiency at the lower modes (Cree data sheet). The hot spot on the XP-G will be tighter and possibly throw a little further. The XM-L die is wider and thus has a wider more floody output. Chances are that you'd end up with a slightly more greenish tint on the XM-L than with the XP-G......but you wouldn't tell that much in the outdoors and only if you had the 2 side-by-side on a white wall.
The Quark X mini outsells the Quark mini XP-G but after seeing both at the same time I think I'd prefer the XP-G version and it's $10 less too. There is 2 benefits to the XM-L LEDs...........one is that it is 20% more efficient but only at the higher output. At low and medium output its basically identical. 2nd benefit is that it is a more floody output if that is what you prefer. Tint wise, I prefer the XP-G's. On high power flashlights that are bigger and have deeper reflectors, I'd take the XM-L over the XP-G. On single cell AA, if anyone offered XM-L, I doubt I'd bother with it. Single cell CR123 XM-L, 3 volt is getting in the area where its acceptable where it can be driven to its capability (ie: at the higher outputs where it is more efficient than XP-G). I think cost is a big factor to consider. If both were the same cost then it boils down to preference.
