It works great on rechargeables - better than with alkalines. Increased run time, same brightness, and no problems at all so far. This has also been true of other regularted/boosted 2 AA LED lights I have: the XM3 and the Costco both.
Come to think of it, also true of my one AA and one AAA lights as well. My direct drive lights (Gerber LXl.0, PT attitude, and some Chinese multi-LED lights) are a little less bright than with fresh alkalines, but more consistent over the battery life. I understand other people have different experience, including having nimh's damage some of their lights due to lower internal resistance, but not for me so far.