Rough ballpark - 900 to 1000 Lumens? I'm basing that on what an XM-L2 puts out per Match's test at 1.4A and rounding down for losses in reflector & lens. Rough guess on run time: 2150mAh (per ledoman's test) / 1400mA current draw = 1.5hr. A "good" battery pack would get you closer to 3.7hrs! OR a good 2 cell battery pack would get you close to 2hrs.
-Garry