Unlike most lights who's output starts to degrade from the moment their turned on my XP-L 5000K model took a while to reach its max output. Output on my XP-L light increased significantly afte 30 sec. and I'm guessing this may be why your measurements don't match those of others tests. My SST20 version did this also but to a lesser extent. For reference my crude bounce tests showed about 1500 lumens for the XP-L and 750 lumens for the SST20.